In 1996, Ibarra became a national deputy and Secretary of the Frepaso block in the Chamber. In 1999, she was elected to the Senate. In 2000, she became a city councillor in Buenos Aires, taking a leading role in her brother's administration. In 2001, she was re-elected to the Senate. Since 2003, she has been a supporter of PeronistPresidentNéstor Kirchner.
In August 2004, Ibarra proposed legislation to legalise abortion. In 2007, she suggested legislative changes to permit same-sex marriage.
In 2007, Ibarra stepped down from the Senate and was re-elected as a national deputy for Buenos Aires, second on the list of Kirchner's Front for Victory.