Elections in Mexico

Elections in Mexico determine who, on the national level, takes the position of the head of state – the president – as well as the legislature.

The President of Mexico is elected for a six-year term by the people. The candidate who wins the most votes is elected president even if he or she does not have an absolute majority.

Since no President can serve more than a single term in office, every presidential election in Mexico is a non-incumbent election.

The Congress of the Union (Congreso de la Unión) has two chambers. The Chamber of Deputies (Cámara de Diputados) has 500 members, elected for a three-year term, 300 of whom are elected in single-seat constituencies by plurality, with the remaining 200 members elected by proportional representation in 5 multi-state, 40-seat constituencies. The 200 PR-seats are distributed generally without taking account the 300 plurality-seats (Parallel voting), but since 1996 a party cannot get more seats overall than 8% above its result for the PR-seats (a party must win 42% of the votes for the PR-seats to achieve an overall majority). There are two exceptions on this rule: first, a party can only lose PR-seats due to this rule (and no plurality-seats); second, a party can never get more than 300 seats overall (even if it has more than 52% of the votes for the PR-seats).

The Chamber of Senators (Cámara de Senadores) has 128 members, elected for a six-year term, 96 of them in three-seat constituencies (corresponding to the nation's 31 states and one Federal District) and 32 by proportional representation on a nationwide basis. In the state constituencies, two seats are awarded to the plurality winner and one to the first runner-up.

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