Turnout: 47.72%
About this election
The legislative election of 7 June 2015 renewed all 500 seats of Mexico's Chamber of Deputies at the midpoint of President Enrique Peña Nieto's term. It was a midterm referendum on his government, held amid disillusionment over corruption, the still-raw Ayotzinapa case and a sluggish economy. The governing Institutional Revolutionary Party (PRI) remained the largest force but lost ground, while the election marked the spectacular debut of two new parties: López Obrador's Morena and a wave of independent candidacies, one of which captured a governorship for the first time in Mexican history.
The Chamber of Deputies has 500 members elected for three-year terms by a mixed system: 300 are chosen by first-past-the-post in single-member districts, and 200 are allocated by proportional representation from closed party lists in five large regional constituencies. The proportional tier corrects the disproportionality of the district races, and a cap prevents any single party from holding more than 8% of seats above its vote share. To register and keep its national registration, a party must clear a 3% threshold. The election was the first run under the 2014 reform that created the INE and, for the first time, allowed independent candidates and re-election of legislators.
The PRI defended the legislative majority underpinning Peña Nieto's "Pacto por México" reform agenda. The PAN and the left-wing PRD, the traditional opposition, both struggled to capitalise on the government's unpopularity — the PRD in particular was damaged by its association, through a local mayor, with the Ayotzinapa atrocity in Guerrero. Into that space stepped Morena, contesting its first election, and a crop of independents led by Jaime "El Bronco" Rodríguez in Nuevo León. The campaign was marred by violence, with several candidates murdered, and by an attempted boycott by dissident teachers in the south.
The PRI took 30.65% of the vote and 203 seats; with its allies the Green Party (PVEM, 47 seats) and New Alliance (11), it preserved a working majority. The PAN won 109 seats on 22.07%, while the PRD slumped to 55. Morena, on its debut, took 8.81% and 35 seats — overtaking the PRD in Mexico City — and the Green Party and Citizens' Movement (25 seats) also advanced. An independent won a seat for the first time. Turnout was 47.7%, typical for a Mexican midterm.
The result let Peña Nieto govern on, but Morena's rise and the PRD's collapse foreshadowed the realignment of the left behind López Obrador. "El Bronco" Rodríguez's victory in the Nuevo León governor's race showed the appetite for outsiders. Three years later, the same forces that surfaced in 2015 would converge to hand AMLO and Morena a sweeping victory in the 2018 general election.
Compiled and reviewed by Bartłomiej Paruzel, Election Data Analyst, from official results. See our data methodology.