Congressman
In the 2015 legislative election, Kirchner ran for a seat in the National Chamber of Deputies as the first candidate in the Front for Victory (FPV) list in Santa Cruz Province. Although the FPV came second in the election, with 46.30% of the vote Kirchner received enough votes to be elected. During his 2015–2019 term, he was appointed as the opposition's representative in the Bicameral Commission for the control of the decrees of necessity and urgency. He was also appointed to the parliamentary commissions on Energy and Fuels, Mining, Impeachments, and Freedom of Expression. During his first three years in office, he introduced 23 bills to the chamber and co-signed two resolutions. In that period he voted affirmatively 186 times, negatively 115 times, abstained 9 times and had 141 absences.
In the 2019 legislative election, Kirchner ran for re-election in Buenos Aires Province instead of Santa Cruz. He was the fifth candidate in the party list of the newly formed Frente de Todos, which received 52.64% of the vote – enough for Kirchner to be elected. Upon taking office, he became president of the unified Frente de Todos parliamentary bloc. On February 1, 2022, Kirchner resigned as President of the Frente de Todos bloc over a disagreement with President Alberto Fernandez over his government's deal with the International Monetary Fund.
In December 2021, he was elected president of the Buenos Aires Province Justicialist Party.
