Election Resources on the Internet: Federal Elections in Mexico

Mexican voters went to the polls on Sunday, July 1^st, 2018 to choose a new President of the United Mexican States, as well as members of the country's bicameral legislature, the Union Congress. An overview of the Mexican electoral system is presented here.

	President		Senate		Chamber of Deputies

July 1^st, 2018	Results	Election Map	Results	Election Map	Results	Election Map

June 7, 2015					Results	Election Map

July 1^st, 2012	Results	Election Map	Results	Election Map	Results	Election Map

July 5, 2009					Results	Election Map

July 2, 2006	Results	Election Map	Results	Election Map	Results	Election Map

July 6, 2003					Results	Election Map

July 2, 2000	Results	Election Map	Results	Election Map	Results	Election Map

July 6, 1997			Results		Results	Election Map

As set forth by the 1917 constitution, Mexico - known officially as the United Mexican States - is a representative, democratic and federal republic. Both the federal government and the governments of Mexico's 32 federal entities - 31 states and Mexico City (previously the Federal District) - consist of executive, legislative and judicial branches.

Supreme executive authority is vested in one individual, the President of the United Mexican States, directly elected by universal adult suffrage for a term of six years. The president - who may not be re-elected - is chosen by the plurality or first-past-the-post method, under which the candidate obtaining the largest number of votes on a nationwide basis is elected to office.

The legislature of Mexico, the Union Congress, consists of a lower house, the Chamber of Deputies, and an upper house, the Senate.

The Chamber of Deputies is composed of 500 members directly elected for a three-year term of office, and originally could not be immediately re-elected. A total of 300 seats are elected in single-member districts by the first-past-the-post method; every federal entity has a minimum of two single-member seats. The remaining 200 seats are apportioned at the national level according to the largest remainder method of proportional representation; these are subsequently distributed among five multi-member constituencies.

In order to participate in the apportionment of Chamber of Deputies proportional seats, a political party must field candidates in at least 200 single-member districts, and receive at least three (previously two) percent of the total number of votes cast for proportional lists, including invalid ballots. However, no political party may receive more than 300 seats in the Chamber of Deputies, and generally speaking no party can be awarded a proportion of Chamber seats exceeding its nationwide vote proportion by more than eight percentage points. Nevertheless, the latter rule does not apply to a party that by virtue of its victories in single-member districts has obtained a proportion of Chamber seats exceeding its vote percentage by more than eight percent.

The Mexican Senate's 128 members are directly elected for a six-year term of office, and originally could not be immediately re-elected either. Each one of Mexico's 32 federal entities chooses three senators: in each entity, the party or coalition with the largest number of votes receives two seats, and the party or coalition in second place obtains one seat. The remaining 32 seats are apportioned in a single, nationwide constituency by the largest remainder method of proportional representation, among lists polling at least two percent of the vote, taking into account invalid ballots.

The members of both houses of the Union Congress chosen from 2018 onwards may be re-elected for consecutive terms of up to twelve years, provided they are nominated by the same political party or as independent candidates, if they were first elected as such.

Since its foundation as a government party in 1929 until 1988, the Partido Revolucionario Institucional (PRI; Institutional Revolutionary Party) - originally the Partido Nacional Revolucionario (PNR; National Revolutionary Party) and subsequently (from 1938 to 1946) the Partido de la Revolución Mexicana (PRM; Party of the Mexican Revolution) - enjoyed a near-absolute domination of Mexico's political life. Although there were a number of opposition parties - most notably among them the right-of-center Partido Acción Nacional (PAN; National Action Party), founded in 1939 - none had been able to effectively challenge the political hegemony of PRI, which possessed full control of the governmental apparatus - including the electoral bodies - and therefore had the means to prevail at the polls, legally or otherwise.

In 1987, a dissident group within the ruling party known as the Corriente Democrática (Democratic Current), led by Cuauhtémoc Cárdenas - a former state governor and son of former president Lázaro Cárdenas - and Porfirio Muñoz Ledo, unsuccessfully sought to have PRI's presidential candidate in 1988 chosen in an open election among party members, rather than appointed by the incumbent president. Cárdenas was subsequently expelled from the PRI, but challenged the ruling party in the 1988 election as the presidential candidate of the Frente Democrático Nacional (FDN; National Democratic Front), a coalition of left-wing parties. According to the official election results, which were delayed for several days due to an alleged (and suspicious) malfunction of the Federal Electoral Commission's computer system, Cárdenas received 31.1% of the vote - at the time, the highest figure ever attained by an opposition presidential candidate since 1929; PAN obtained 17.1%. Officially, PRI won the election with 50.4% of the vote, but this was its lowest vote percentage up to that point, and Mexico's political party system was transformed into a three-party system that has persisted to this day, initially with PAN on the right, the Partido de la Revolución Democrática (PRD; Party of the Democratic Revolution) - the FDN's successor, founded in 1989 by Cuauhtémoc Cárdenas - on the left, and PRI in the middle.

PRI retained the presidency in the 1994 election, but in 1997 it lost the absolute majority in the Chamber of Deputies. The opposition parties set aside their ideological differences and joined forces to take control of the Union Congress' Lower House. In the July 2, 2000 election, seventy-one years of PRI governments came to an end with the election of Vicente Fox Quesada - candidate of the Alianza por el Cambio (Alliance for Change), an electoral coalition of PAN and the Partido Verde Ecologista de México (PVEM; Green Ecologist Party of Mexico) - as President of the United Mexican States. Nonetheless, PRI retained a relative majority in the Senate, while in the Chamber of Deputies the Alliance for Change won more seats than PRI, but not an absolute majority. However, in the July 6, 2003 election, PRI - now in a partial coalition with PVEM - scored a decisive victory over PAN, but the PRI-PVEM coalition also fell short of an absolute majority in the Chamber of Deputies.

According to official results of the July 2, 2006 presidential election, PAN candidate Felipe Calderón secured a narrow majority of 0.58%, or 243,934 votes over Andrés Manuel López Obrador, candidate of the Coalición por el Bien de Todos (Coalition for the Good of All) of PRD, the Partido del Trabajo (PT; Labor Party) and Convergencia (C; Convergence). López Obrador, who demanded a full recount of all ballots cast in the election and refused to concede victory to PAN, challenged the vote outcome. However, Roberto Madrazo, candidate of the Alianza por México (Alliance for Mexico) formed by PRI and PVEM - who finished in a distant third place - acknowledged his defeat.

As set forth by Article 99 of the Mexican Constitution, the Electoral Tribunal of the Federal Judiciary - the maximum jurisdictional authority in electoral matters - resolves in definite and unimpeachable form challenges presented about the election of the President of the United Mexican States. In addition, it issues the final results of the presidential election, once it resolves the challenges on the election brought to its attention. It proceeds to formulate the declaration of validity of the election and who is president-elect, who will be the candidate who obtained the greatest number of votes.

On Saturday, August 5, 2006, the Electoral Tribunal ruled unanimously against a total recount of ballots requested by the Coalición por el Bien de Todos, but ordered a partial recount in 11,839 voting stations (out of 130,477) with mathematical errors on their tally sheets. However, the outcome of the presidential election didn't change significantly after the partial recount, and on Tuesday, September 5, 2006, the Electoral Tribunal unanimously declared Felipe Calderón the winner of the presidential election with a slightly reduced lead of 0.56% - 233,831 votes - over Andrés Manuel López Obrador, who nonetheless has refused to recognize the decision.

Meanwhile, in the 2006 congressional vote, PAN decisively outpolled the Coalition for the Good of All in both the Senate and the Chamber of Deputies, while the Alliance for Mexico slipped to third place, albeit with better results than in the presidential election; in fact, the PRI-PVEM alliance won a larger number of Senate seats than the PRD-PT-C coalition. PAN won seat pluralities in both the Senate and the Chamber, but in the July 5, 2009 election, PRI and PVEM - once more in a partial coalition - defeated the ruling party and secured a joint absolute majority in the Chamber of Deputies, while PRD, beset by infighting, finished in a distant third place.

After twelve years out of power, PRI recovered the presidency in 2012, when its candidate Enrique Peña Nieto prevailed over López Obrador - nominated once more by PRD, PT and the Movimiento Ciudadano (MC; Citizens' Movement, formerly Convergence) - and PAN nominee Josefina Vázquez Mota, who finished third in the presidential contest. In addition, the Compromiso por México (Commitment to Mexico) coalition of PRI and PVEM won a plurality of seats in both houses of the Union Congress.

In the 2015 election, the PRI-PVEM coalition secured exactly half the seats in the Chamber of Deputies. Nevertheless, in the Federal District (Mexico City) Lopez Obrador's new left-wing party, the National Regeneration Movement (MORENA) won the largest number of votes as well as single-member seats.