2027 Mexican legislative election

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. 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. 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. == Electoral system ==

The National Electoral Institute (INE) oversees federal elections in Mexico. Its responsibilities include organizing election day logistics, producing and distributing electoral materials, counting votes, and certifying the election results. The 500 members of the Chamber of Deputies are elected in two ways: 300 are elected in single-member constituencies by plurality vote, and the remaining 200 are elected by proportional representation in five multi-member districts, with seats divided according to Hamilton's method. No political party may hold more than 300 seats in total, and proportional representation seats may not be allocated in a manner that results in a party exceeding its national vote share by more than eight percentage points. Deputies are elected for three-year terms and will serve in the 67th Congress. == Political parties and coalitions ==

Six national political parties are registered with the INE and are eligible to participate in the 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), and the National Regeneration Movement (Morena). The General Law of Political Parties stipulates that national political parties can form coalitions for elections by submitting a coalition agreement to the electoral authority. Parties cannot join coalitions in their first election. Summary 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 official party status, these groups were required to affiliate at least 0.26% of the national electoral roll, 256,030 registered voters, by 28 February 2026, and to hold either 20 statewide assemblies, each with a minimum attendance of 3,000 participants, or 200 district-level assemblies with at least 300 participants each, by 15 February 2026, in accordance with electoral law. == Opinion polls ==