Turnout: 61.04%
About this election
The Chamber of Deputies election of 2 June 2024, held alongside Claudia Sheinbaum's presidential landslide, returned the governing Morena coalition to power with its largest legislative majority yet — close to the two-thirds supermajority that would allow it to amend the constitution. The result, amplified by Mexico's seat-allocation rules, gave the incoming administration extraordinary legislative reach and reopened debate over the over-representation of the leading bloc.
The 500 deputies are elected by the familiar mixed system: 300 single-member districts plus 200 proportional seats across five regional constituencies, for three-year terms. A constitutional cap limits any single party to at most 8 percentage points of seat share above its vote share. In 2024 the way coalition seats were distributed among Morena, the PT and the PVEM allowed the governing bloc's combined seat share (around 73%) to run well ahead of its roughly 54% combined vote, prompting a fierce dispute before the electoral tribunal over whether the cap had been respected.
The governing "Sigamos Haciendo Historia" coalition (Morena, PT, PVEM) ran on continuity with López Obrador's social programmes and Sheinbaum's commanding lead. The opposition "Fuerza y Corazón por México" (PAN, PRI, PRD) campaigned on rising organised-crime violence and the erosion of independent institutions, while Citizens' Movement again stood apart. As at the presidential level, the campaign saw an unprecedented wave of violence against candidates for local and federal office.
The Sigamos Haciendo Historia coalition took roughly 54% of the combined vote and 364 of 500 seats; Morena alone won 236. The opposition Fuerza y Corazón coalition managed just 108 seats and Citizens' Movement 27. The electoral tribunal upheld the allocation, leaving the governing bloc two or three seats short of two-thirds in its own right but able to reach it with sympathetic independents.
The near-supermajority let the new Congress, which convened on 1 September 2024 before Sheinbaum took office, pass a backlog of constitutional reforms inherited from López Obrador — above all the judicial reform introducing the popular election of judges. The scale of Morena's congressional dominance, and the mechanics that produced it, became a defining controversy of the new sexenio and a rallying point for an opposition reduced to its weakest position in decades.
The dispute turned on a detail of Mexico's over-representation cap. The constitution limits any single party to a seat share no more than eight points above its vote share — but the limit is applied to each party individually, not to a coalition as a whole. By allocating its district victories among Morena, the PT and the PVEM, the governing alliance kept each partner within its own eight-point ceiling while lifting the coalition's combined seat share (around 73%) roughly nineteen points above its combined vote of about 54%. The opposition argued to the electoral tribunal (TEPJF) that this defeated the purpose of the cap; the tribunal, by majority, accepted the party-by-party reading and confirmed the allocation shown above. The episode reopened a long-running debate over whether the rule should be recalculated at coalition level.
The result is best read against the previous midterm. In 2021 Morena's coalition had lost the two-thirds supermajority it won in 2018, retaining only a working simple majority in the Chamber and forcing López Obrador to shelve several constitutional projects. The 2024 landslide, riding Sheinbaum's presidential margin, reversed that: the bloc surged back to the edge of two-thirds and unlocked precisely the constitutional agenda that had been stalled since 2021. Our 2021 Chamber page shows the earlier composition for comparison, and the Mexico hub collects every federal contest since 2015 side by side.
Compiled and reviewed by Bartłomiej Paruzel, Election Data Analyst, from official results. See our data methodology.