Class 2Class 2 U.S. senators belong to the electoral cycle that has recently been contested in 2002, 2008, 2014, and 2020. The next election will be in 2026.
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C
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Class 3Class 3 U.S. senators belong to the electoral cycle that has recently been contested in 2004, 2010, 2016, and 2022. The next election will be in 2028.
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#
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Senator
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Party
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Dates in office
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Electoral history
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T
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T
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Electoral history
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Dates in office
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Party
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Senator
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#
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Vacant
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Aug 1, 1876 – Nov 15, 1876
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Colorado did not elect its senators until three months after statehood.
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1
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44th
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1
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Colorado did not elect its senators until three months after statehood.
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Aug 1, 1876 – Nov 15, 1876
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Vacant
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1
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![](//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Henry_Moore_Teller_c._1902.jpg/100px-Henry_Moore_Teller_c._1902.jpg) Henry M. Teller
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Republican
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Nov 15, 1876 – Apr 17, 1882
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Elected in 1876.
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Elected in 1876.Retired.
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Nov 15, 1876 – Mar 3, 1879
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Republican
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![]() Jerome B. Chaffee
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1
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Elected to next term in 1876 or 1877.Resigned to become U.S. Secretary of the Interior.
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2
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45th
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46th
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2
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Elected in 1879.Lost re-nomination.
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Mar 4, 1879 – Mar 3, 1885
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Nathaniel_P._Hill_-_Brady-Handy.jpg/100px-Nathaniel_P._Hill_-_Brady-Handy.jpg) Nathaniel P. Hill
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2
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47th
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2
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![](//upload.wikimedia.org/wikipedia/commons/thumb/5/50/George_M._Chilcott_-_Brady-Handy.jpg/100px-George_M._Chilcott_-_Brady-Handy.jpg) George M. Chilcott
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Republican
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Apr 17, 1882 – Jan 27, 1883
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Appointed to continue Teller's term.Did not run to finish the term.
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3
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![](//upload.wikimedia.org/wikipedia/commons/thumb/4/42/Horace_Austin_Warner_Tabor_-_Brady-Handy.jpg/100px-Horace_Austin_Warner_Tabor_-_Brady-Handy.jpg) Horace Tabor
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Republican
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Jan 27, 1883 – Mar 3, 1883
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Elected to finish Teller's term.Retired.
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4
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![](//upload.wikimedia.org/wikipedia/commons/thumb/b/b5/ThomasMBowen.jpg/100px-ThomasMBowen.jpg) Thomas M. Bowen
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Republican
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Mar 4, 1883 – Mar 3, 1889
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Election date unknown.Unknown if retired or lost re-election.
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3
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48th
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49th
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3
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Elected in 1885.
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Mar 4, 1885 – Mar 3, 1909
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Henry_Moore_Teller_c._1902.jpg/100px-Henry_Moore_Teller_c._1902.jpg) Henry M. Teller
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3
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50th
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5
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![](//upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Edward_Oliver_Wolcott.jpg/100px-Edward_Oliver_Wolcott.jpg) Edward O. Wolcott
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Republican
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Mar 4, 1889 – Mar 3, 1901
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Elected in 1889.
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4
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51st
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52nd
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4
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Re-elected in 1891.
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53rd
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Re-elected in 1895.Lost re-election.
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5
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54th
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55th
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5
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Re-elected in 1897.[1]
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Silver Republican
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56th
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6
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![](//upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Thomas_MacDonald_patterson.jpg/100px-Thomas_MacDonald_patterson.jpg) Thomas M. Patterson
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Democratic
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Mar 4, 1901 – Mar 3, 1907
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Elected in 1901.Retired.
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6
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57th
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58th
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6
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Re-elected in 1903.Retired.
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Democratic
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59th
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7
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![](//upload.wikimedia.org/wikipedia/commons/thumb/0/09/Simon_Guggenheim_cph.3a02257.jpg/100px-Simon_Guggenheim_cph.3a02257.jpg) Simon Guggenheim
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Republican
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Mar 4, 1907 – Mar 3, 1913
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Elected in 1907.Retired.
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7
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60th
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61st
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7
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Elected in 1909.Died.
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Mar 4, 1909 – Jan 11, 1911
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/e/ee/CharlesJHughes.jpg/100px-CharlesJHughes.jpg) Charles J. Hughes Jr.
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4
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Jan 11, 1911 – Jan 15, 1913
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Vacant
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62nd
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Elected to finish Hughes's term.
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Jan 15, 1913 – Mar 3, 1921
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/4/41/Charles_Spalding_Thomas.jpg/100px-Charles_Spalding_Thomas.jpg) Charles S. Thomas
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5
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8
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![](//upload.wikimedia.org/wikipedia/commons/thumb/1/1a/John_Shafroth.gif/100px-John_Shafroth.gif) John F. Shafroth
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Democratic
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Mar 4, 1913 – Mar 3, 1919
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Elected in 1913.Lost re-election.
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8
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63rd
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64th
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8
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Re-elected in 1914.Lost re-election.
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65th
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9
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![](//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Lawrence_Cowle_Phipps2.jpg/100px-Lawrence_Cowle_Phipps2.jpg) Lawrence C. Phipps
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Republican
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Mar 4, 1919 – Mar 3, 1931
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Elected in 1918.
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9
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66th
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67th
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9
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Elected in 1920.Died.
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Mar 4, 1921 – Mar 24, 1923
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Samuel_Danford_Nicholson.jpg/100px-Samuel_Danford_Nicholson.jpg) Samuel D. Nicholson
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6
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68th
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Mar 24, 1923 – May 17, 1923
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Vacant
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Appointed to continue Nicholson's term.Retired.
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May 17, 1923 – Nov 30, 1924
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Alva_Blanchard_Adams_2.jpg/100px-Alva_Blanchard_Adams_2.jpg) Alva B. Adams
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7
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Elected to finish Nicholson's term.Lost renomination.
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Dec 1, 1924 – Mar 3, 1927
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Rice_W._Means.jpg/100px-Rice_W._Means.jpg) Rice W. Means
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8
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Re-elected in 1924.Retired.
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10
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69th
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70th
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10
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Elected in 1926.Died.
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Mar 4, 1927 – Aug 27, 1932
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/d/d3/Charles_Winfield_Waterman.jpg/100px-Charles_Winfield_Waterman.jpg) Charles W. Waterman
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9
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71st
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10
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![](//upload.wikimedia.org/wikipedia/commons/thumb/5/5e/Senator_Edward_Prentiss_Costigan.jpg/100px-Senator_Edward_Prentiss_Costigan.jpg) Edward P. Costigan
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Democratic
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Mar 4, 1931 – Jan 3, 1937
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Elected in 1930.Retired.
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11
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72nd
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Aug 27, 1932 – Sep 26, 1932
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Vacant
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Appointed to continue Waterman's term.Lost election to finish Waterman's term.
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Sep 26, 1932 – Dec 6, 1932
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/2/2f/Senator_Walter_Walker.jpg/100px-Senator_Walter_Walker.jpg) Walter Walker
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10
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Elected to finish Waterman's term.Lost election to next term.
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Dec 7, 1932 – Mar 3, 1933
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Karl_C_Schuyler.jpg/100px-Karl_C_Schuyler.jpg) Karl C. Schuyler
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11
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73rd
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11
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Elected in 1932.
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Mar 4, 1933 – Dec 1, 1941
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Alva_Blanchard_Adams_2.jpg/100px-Alva_Blanchard_Adams_2.jpg) Alva B. Adams
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12
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74th
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11
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![](//upload.wikimedia.org/wikipedia/commons/thumb/d/da/Edwin_Johnson.jpg/100px-Edwin_Johnson.jpg) Edwin C. Johnson
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Democratic
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Jan 3, 1937 – Jan 3, 1955
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Elected in 1936.
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12
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75th
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76th
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12
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Re-elected in 1938.Died.
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77th
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Dec 1, 1941 – Dec 20, 1941
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Vacant
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Appointed to continue Adams's term.Elected in 1942 to finish Adams's term.
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Dec 20, 1941 – Jan 3, 1957
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Eugene_Millikin.jpg/100px-Eugene_Millikin.jpg) Eugene Millikin
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13
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Re-elected in 1942.
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13
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78th
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79th
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13
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Re-elected in 1944.
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80th
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Re-elected in 1948.Retired to run for Governor.
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14
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81st
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82nd
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14
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Re-elected in 1950.Retired
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83rd
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12
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![](//upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Gordon_L_Allott.jpg/100px-Gordon_L_Allott.jpg) Gordon Allott
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Republican
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Jan 3, 1955 – Jan 3, 1973
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Elected in 1954.
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15
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84th
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85th
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15
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Elected in 1956.Lost re-election.
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Jan 3, 1957 – Jan 3, 1963
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/f/f9/JohnACarroll.jpg/100px-JohnACarroll.jpg) John A. Carroll
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14
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86th
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Re-elected in 1960.
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16
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87th
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88th
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16
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Elected in 1962.
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Jan 3, 1963 – Jan 3, 1975
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Republican
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![](//upload.wikimedia.org/wikipedia/commons/thumb/5/55/PHDominick.jpg/100px-PHDominick.jpg) Peter H. Dominick
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15
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89th
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Re-elected in 1966.Lost re-election.
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17
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90th
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91st
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17
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Re-elected in 1968.Lost re-election.
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92nd
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13
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![](//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/FloydHaskell.jpg/100px-FloydHaskell.jpg) Floyd Haskell
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Democratic
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Jan 3, 1973 – Jan 3, 1979
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Elected in 1972.Lost re-election.
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18
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93rd
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94th
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18
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Elected in 1974.
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Jan 3, 1975 – Jan 3, 1987
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/2/26/Gary_hart.jpg/100px-Gary_hart.jpg) Gary Hart
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16
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95th
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14
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![](//upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Sen_William_L_Armstrong.jpg/100px-Sen_William_L_Armstrong.jpg) William L. Armstrong
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Republican
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Jan 3, 1979 – Jan 3, 1991
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Elected in 1978.
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19
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96th
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97th
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19
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Re-elected in 1980.Retired.
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98th
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Re-elected in 1984.Retired.
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20
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99th
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100th
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20
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Elected in 1986.Retired.
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Jan 3, 1987 – Jan 3, 1993
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Tim_Wirth_%281%29.jpg/100px-Tim_Wirth_%281%29.jpg) Tim Wirth
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17
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101st
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15
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![](//upload.wikimedia.org/wikipedia/commons/thumb/b/b5/HankBrown.jpg/100px-HankBrown.jpg) Hank Brown
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Republican
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Jan 3, 1991 – Jan 3, 1997
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Elected in 1990.Retired.
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21
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102nd
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103rd
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21
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Elected in 1992.Changed parties on March 3, 1995.
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Jan 3, 1993 – Jan 3, 2005
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/7/75/BenNCampbell.jpg/100px-BenNCampbell.jpg) Ben Nighthorse Campbell
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18
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104th
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Republican
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16
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![](//upload.wikimedia.org/wikipedia/commons/thumb/2/26/Wayne_Allard_official_portrait.jpg/100px-Wayne_Allard_official_portrait.jpg) Wayne Allard
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Republican
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Jan 3, 1997 – Jan 3, 2009
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Elected in 1996.
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22
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105th
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106th
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22
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Re-elected in 1998.Retired.
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107th
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Re-elected in 2002.Retired.
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23
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108th
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109th
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23
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Elected in 2004.Resigned to become U.S. Secretary of the Interior.
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Jan 3, 2005 – Jan 20, 2009
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Kensalazar.jpg/100px-Kensalazar.jpg) Ken Salazar
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19
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110th
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17
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![](//upload.wikimedia.org/wikipedia/commons/thumb/2/2b/MarkUdall-Senate_Portrait.jpg/100px-MarkUdall-Senate_Portrait.jpg) Mark Udall
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Democratic
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Jan 3, 2009 – Jan 3, 2015
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Elected in 2008.Lost re-election.
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24
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111th
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Appointed to finish Salazar's term.
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Jan 21, 2009 – present
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Democratic
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![](//upload.wikimedia.org/wikipedia/commons/thumb/2/20/MichaelBennetofficialphoto.jpg/100px-MichaelBennetofficialphoto.jpg) Michael Bennet
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20
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112th
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24
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Elected to a full term in 2010.
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113th
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18
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![](//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Cory_Gardner_official_Senate_portrait.jpeg/100px-Cory_Gardner_official_Senate_portrait.jpeg) Cory Gardner
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Republican
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Jan 3, 2015 – Jan 3, 2021
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Elected in 2014.Lost re-election.
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25
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114th
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115th
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25
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Re-elected in 2016.
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116th
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19
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![](//upload.wikimedia.org/wikipedia/commons/thumb/a/a8/John_Hickenlooper%2C_official_portrait%2C_117th_Congress.jpeg/100px-John_Hickenlooper%2C_official_portrait%2C_117th_Congress.jpeg) John Hickenlooper
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Democratic
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Jan 3, 2021 – present
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Elected in 2020.
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26
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117th
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118th
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26
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Re-elected in 2022.
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119th
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To be determined in the 2026 election.
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27
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120th
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121st
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27
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To be determined in the 2028 election.
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#
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Senator
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Party
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Years in office
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Electoral history
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T
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C
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T
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Electoral history
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Years in office
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Party
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Senator
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#
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Class 2
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Class 3
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