Caldwell was pre-selected by the Liberal National Party (LNP) to run in the seat of Broadwater at the 2012 Queensland state election. In February 2012, a month before the election, he was disendorsed after the party received a complaint from a member of the public about a trip Caldwell had made to a swinger's club.[4] LNP leader Campbell Newman defended the party's decision to dump Caldwell.[5]
In April later that year, Caldwell was elected as the councillor for Division 3 of the City of Gold Coast.[6] He was re-elected in 2016, and then elected as the councillor for Division 4 in 2020.[7][8]
During his time as councillor, in December 2012, while acting mayor of the Gold Coast, Caldwell was accused of assaulting a property developer at a charity function, allegedly grabbing him by the throat, which Caldwell denied.[9]
Following the resignation of former minister Stuart Robert from parliament, Caldwell was selected as the LNP's candidate in Fadden for the by-election, defeating four other nominees in three rounds of voting.[10] Caldwell stated that the by-election would be a way to send a message to Prime Minister Anthony Albanese on issues relating to the economy, saying that he knew he "can be the one they can support in order to deliver for our local community."[11] He was successfully elected in the by-election on 15 July 2023.[12]