Turnout: 81.07%
About this election
Argentina's 2015 legislative elections renewed half of the Chamber of Deputies on 25 October, the same day as the first round of the presidential election. The governing Front for Victory (Frente para la Victoria) remained the largest force in the chamber but lost its majority, while Mauricio Macri's Cambiemos and Sergio Massa's UNA front made gains that foreshadowed the end of Kirchnerism in the executive a month later.
The 257 members of the Chamber of Deputies are elected by closed-list proportional representation (D'Hondt) in 24 constituencies — the 23 provinces plus the City of Buenos Aires — with a 3% district threshold. Only half the chamber is renewed every two years for four-year terms, so 130 seats were at stake in 2015. Seats are apportioned to districts by population, giving Buenos Aires Province and the City of Buenos Aires the largest delegations.
Held alongside the presidential first round, the legislative contest broadly tracked it. The Front for Victory won the most votes nationally, about 37.39%, and 60 of the 130 seats up for election, but well short of the numbers needed to retain control of the chamber. Cambiemos took roughly 35.11% and 47 seats, and Massa's UNA front 17.56% and 17 seats, with provincial parties sharing the remainder.
The result left the incoming Macri government without a majority in either house of Congress, forcing it to negotiate with Peronist governors and blocs throughout its term — a structural weakness that shaped the politics of 2016–2019 and the difficulty of passing its economic programme.
The chamber elected on 25 October told only half the story of that spring-like political moment. On the same day, the Front for Victory's presidential candidate Daniel Scioli finished first but below the threshold for outright victory, sending Argentina to the first presidential run-off actually held in its history — which Mauricio Macri won a month later, 51.34% to 48.66%. Voters thus handed the presidency to Cambiemos while leaving Kirchnerism the largest bloc in the Chamber of Deputies elected the very same day. Because only half the chamber is renewed at each election, the seats not at stake in 2015 still reflected the 2011 and 2013 results, cushioning the governing front's decline and deepening the divided government that followed. Turnout, at 81.07% of registered voters, was among the highest of Argentina's modern legislative elections.
The map mirrored the presidential vote: the Front for Victory dominated the northern provinces and much of the interior, while Cambiemos led in the City of Buenos Aires, Córdoba, Santa Fe and Mendoza. Massa's front drew its strength from Buenos Aires Province, where its Peronist dissidents were rooted.
Official results from Argentina's Cámara Nacional Electoral / Dirección Nacional Electoral (resultados.gob.ar). Vote shares are national aggregates of valid votes; the map shows the leading list in each province, with the full breakdown on click. Per-province seat allocations are not shown.
Compiled and reviewed by Bartłomiej Paruzel, Election Data Analyst, from official results. See our data methodology.