Legislative elections are scheduled to be held in Mexico on 6 June 2027. Voters will elect all 500 members of the Chamber of Deputies, who will serve during the LXVII Legislature (2027–2030). These elections will take place concurrently with the 2027 state elections.

Background

Political background In the 2024 election, Sigamos Haciendo Historia, a coalition that included the National Regeneration Movement (Morena), the Ecologist Green Party of Mexico (PVEM), and the Labor Party (PT), won a majority of seats in Congress. The coalition obtained approximately 73% of the seats in the Chamber of Deputies, winning 256 of the 300 single-member districts and 108 seats through proportional representation, thereby achieving a supermajority in the lower house. In the Senate, the coalition initially fell three seats short of a supermajority; however, subsequent defections allowed it to reach that threshold. This marked the first time since the LIII Legislature that a governing party or coalition held a supermajority in both chambers of Congress.

The same election left the opposition substantially weakened. Fuerza y Corazón por México, the coalition of the National Action Party (PAN), the Institutional Revolutionary Party (PRI), and the Party of the Democratic Revolution (PRD) that had backed presidential candidate Xóchitl Gálvez, won less than a third of the presidential vote. The PRD, founded in 1989 and long the principal party of the Mexican left until the rise of Morena, lost its national registration after taking 1.86% in the presidential race, below the 3% threshold required to retain it, ending 35 years as a national party. The remaining opposition then fragmented further: in October 2025 the PAN's national leader, Jorge Romero, announced that the party would contest the 2027 election on its own, ending the electoral alliance with the PRI that the two had maintained since 2021. The PRI, led by Alejandro Moreno, pressed for a united opposition front, but the PAN and Citizens' Movement (MC), which had run alone in 2024, rejected the proposal, leaving the three parties set to compete separately against the governing coalition.

Following the inauguration of the LXVI Legislature, the ruling coalition used its supermajority to advance a package of constitutional amendments known as "Plan C", originally proposed by former president Andrés Manuel López Obrador and which President Claudia Sheinbaum campaigned on passing during the 2024 presidential election. The coalition frequently employed expedited or "fast-track" legislative procedures, limiting extended committee deliberation and accelerating the approval process. The coalition's control of more than two-thirds of each chamber also left the opposition unable to initiate constitutional challenges, as an Action of Unconstitutionality requires the support of at least 33% of the members of a legislative chamber to be filed. As a result, the coalition was able to approve controversial constitutional reforms along party-line votes, including the 2024 judicial reform, the transfer of the National Guard to military control, the adoption of the constitutional supremacy clause, and the dissolution of several autonomous constitutional bodies. However, by late 2025, the coalition's internal unity also began to weaken. In December 2025, the PT broke ranks for the first time, abstaining on Sheinbaum's revision of Mexico's import and export tariff law. In early 2026, when Sheinbaum pursued an electoral reform that was widely seen as disadvantageous for smaller parties, the PT and PVEM mostly voted against it, marking the first time Morena's coalition partners voted against one of Sheinbaum's constitutional initiatives.

Electoral system

Seat allocation The 500 members of the Chamber of Deputies serve three-year terms and are elected under a mixed system. Three hundred are chosen by plurality in single-member districts. The remaining 200 are elected by proportional representation from regional party lists in five electoral regions of 40 seats each. The lists must observe gender parity, and the regional lists are headed alternately by women and men from one election to the next.

Proportional seats are allocated in each region according to the parties' shares of the vote there, and only parties that win at least 3% of the valid national vote take part in the allocation. Two limits restrict the result: no party may hold more than 300 seats under both principles combined, and no party's share of the chamber may exceed its share of the national vote by more than eight percentage points. A party that would breach either limit loses proportional seats until it complies, and the surplus seats pass to the other parties.

Because votes for coalition candidates are counted for each party according to the emblem under which they were cast, the limits apply to each coalition partner separately rather than to the coalition as a whole. From 1996, the limits had covered coalitions as well, as the electoral code treated a coalition as a single party when allocating seats. A new code in January 2008 dropped that provision, and the National Electoral Institute (INE) applied the limits party by party at every election from 2009 onward. The cap was disputed after the 2024 election, when the INE's General Council voted eight to three for an allocation that gave the National Regeneration Movement (Morena), the Ecologist Green Party of Mexico (PVEM), and the Labor Party (PT) 364 of the 500 seats, a two-thirds majority. The three councilors in the minority had proposed a stricter reading of the cap, under which a party could exceed its vote share by no more than 8% of that share; under that reading the three parties would have had 317 seats. The National Action Party (PAN), the Institutional Revolutionary Party (PRI), and Citizens' Movement (MC) filed 8,662 challenges, arguing that the eight-point margin should apply to the coalition, but the Electoral Tribunal of the Federal Judiciary (TEPJF) upheld the allocation by four votes to one.

Candidates and coalitions Parties may form coalitions for the 300 district seats, in three forms: total, covering all 300 districts; partial, covering at least 150; and flexible, covering at least 75. Coalition agreements must be filed with the INE by 4 January 2027, the day pre-campaigns open. Newly registered parties may not join a coalition until they have contested their first election, so Building Societies of Peace (PAZ) and SOMOS must run alone in 2027, and each must win at least 3% of the national vote to keep its registration.

Each party must notify the INE of its candidate-selection procedure 30 days before pre-campaigns begin, and its internal process must apply criteria on gender parity, affirmative action, and consecutive reelection. Parties must choose their district candidates by 19 February 2027 and their list candidates by 26 February, and resolve internal appeals by 12 March. Deputies may serve up to four consecutive terms; a 2025 constitutional amendment bars immediate reelection from the 2030 elections onward, making 2027 the last federal election at which sitting deputies may seek a further consecutive term.

Independent candidates may contest district seats. Aspirants have until 13 December 2026 to give notice of their intent and must then gather signatures equal to 2% of the district's electoral roll by 12 February 2027.

Voters and administration The National Electoral Institute (INE) organizes the election, which is held on the same day as local elections across the country; federal and local ballots are cast at the same location. As of 27 August 2026, the electoral roll held 100,862,772 voters, the largest in the country's history, and the INE planned to install 176,741 polling stations. Mexicans living abroad cannot vote for federal deputies.

Disputes are resolved by the Electoral Tribunal of the Federal Judiciary (TEPFJ), and the INE assigns the proportional representation seats once the tribunal has ruled on all challenges to the district results. The 2027 calendar schedules that allocation for 1 to 23 August 2027; the deputies elected will form the LXVII Legislature.

Political parties and coalitions

Eight national political parties are registered with the INE and are eligible to participate in federal elections: the National Action Party (PAN), the Institutional Revolutionary Party (PRI), the Labor Party (PT), the Ecologist Green Party of Mexico (PVEM), Citizens' Movement (MC), the National Regeneration Movement (Morena), Building Societies of Peace (PAZ), and We Are (SOMOS).

Summary PartyLeaderIdeology2024 result vote (%)SeatsNational Regeneration MovementAriadna Montiel Reyes42.40%Ecologist Green Party of MexicoKaren Castrejón TrujilloGreen politics8.72%National Action PartyJorge Romero Herrera17.55%Labor PartyAlberto Anaya5.68%Institutional Revolutionary PartyAlejandro Moreno Cárdenas11.57% Citizens' MovementJorge Máynez11.34%Building Societies of PeaceArmando González EscotoDid not existWe AreGuadalupe Acosta NaranjoDid not exist

Creation of new parties In January 2025, the registration period opened for political organizations seeking recognition as national political parties, during which 89 organizations formally registered their intent to do so. To obtain registration, an organization had to affiliate at least 0.26% of the national electoral roll—256,030 voters—by 28 February 2026. It also had to hold either 20 state assemblies attended by at least 3,000 people each, or 200 district assemblies of at least 300 people each, by 15 February 2026, in accordance with electoral law.

Of the 89 organizations, 31 withdrew, and five formally applied for registration in February 2026; four of them met the affiliation and assembly requirements. On 24 June 2026, the INE's Commission on Prerogatives and Political Parties recommended that the General Council grant national-party registration to these four. The following day, the General Council approved two of them—Building Societies of Peace (PAZ) and We Are Mexico (Somos MX)—and rejected the applications of México Tiene Vida and Que Siga la Democracia. PAZ was a successor to the Social Encounter Party and the Solidarity Encounter Party, while Somos MX grew out of the Marea Rosa (), a citizens' movement that arose in 2022 in defence of the INE's autonomy against an electoral reform proposed by President Andrés Manuel López Obrador and that backed Xóchitl Gálvez in the 2024 presidential election.

The General Council denied registration to México Tiene Vida by six votes to five and to Que Siga la Democracia by seven votes to four. It found that ministers of religion had participated in at least 58 of México Tiene Vida's assemblies, conduct prohibited by electoral law, and cited financial irregularities including an undeclared corporate donation and an attempted bribe of an electoral official. Que Siga la Democracia was rejected for 92 affiliation records that contained altered photographs and falsified voter credentials, along with unreported expenditures and payments to citizens to attend its assemblies. A last-minute report by the Financial Intelligence Unit (UIF) also alleged that resources had been channelled through shell companies to the organization's president, Édgar Garza, an allegation he denied. Several INE councillors criticised the UIF report as irregular and untimely.

Opinion polls

References