Senate of the Republic (Mexico) in the context of 2018 Mexican general election

The Congress of the Union (Spanish: Congreso de la Unión, pronounced [koŋˈɡɾeso ðe lawˈnjon]), formally known as the General Congress of the United Mexican States (Congreso General de los Estados Unidos Mexicanos), is the legislature of the federal government of Mexico. It consists of two chambers: the Senate of the Republic and the Chamber of Deputies. Its 628 members (128 senators and 500 deputies) meet in Mexico City.

The politics of Mexico function within the framework of the federal presidential representative democratic republic whose government is based on a multi-party congressional system, where the President of Mexico is both head of state and head of government. The federal government represents the United Mexican States. It is divided into three branches: executive, legislative, and judicial, established by the Political Constitution of the United Mexican States, published in 1917. The constituent states of the federation must also have a republican government based on a congressional system established by their respective constitutions.

Executive power is exercised by the executive branch, headed by the President, who is advised by a cabinet of secretaries independent of the legislature. Legislative power is vested in the Congress of the Union, a two-chamber legislature comprising the Senate of the Republic and the Chamber of Deputies. Judicial power is exercised by the judiciary, consisting of the Supreme Court of Justice of the Nation, the Council of the Federal Judiciary, and the collegiate, unitary, and district tribunals.

Adolfo López Mateos (Spanish pronunciation: [aˈðolfo ˈlopes maˈteos] ; 26 May 1909 – 22 September 1969) was a Mexican politician and lawyer who served as President of Mexico from 1958 to 1964. Previously, he served as Secretary of Labor and Social Welfare from 1952 to 1957 and a Senator from the State of Mexico from 1946 to 1952.

Beginning his political career as a campaign aide of José Vasconcelos during his run for president, López Mateos encountered repression from Plutarco Elías Calles, who attempted to maintain hegemony within the National Revolutionary Party (PNR). He briefly abandoned politics and worked as a professor at the Autonomous University of Mexico State, becoming a member of the PNR (renamed Party of the Mexican Revolution) in 1941. López Mateos served as senator for the State of Mexico from 1946 to 1952 and Secretary of Labor during the administration of Adolfo Ruiz Cortines from 1952 to 1957. He secured the party's presidential nomination and won in the 1958 general election.

Gustavo Díaz Ordaz Bolaños (Spanish pronunciation: [ɡusˈtaβo ˈði.as oɾˈðas]; 12 March 1911 – 15 July 1979) was a Mexican politician and member of the Institutional Revolutionary Party (PRI). He served as the President of Mexico from 1964 to 1970. Previously, he served as a member of the Chamber of Deputies for Puebla's 1st district, a senator of the Congress of the Union for Puebla, and Secretary of the Interior.

Díaz Ordaz was born in San Andrés Chalchicomula, and obtained a law degree from the University of Puebla in 1937 where he later became its vice-rector. He represented Puebla's 1st district in the Chamber of Deputies from 1943 to 1946. Subsequently, he represented the same state in the Chamber of Senators from 1946 to 1952 becoming closely acquainted with then-senator Adolfo López Mateos. Díaz Ordaz was a CIA asset, known by the cryptonym, LITEMPO-2.

The National Action Party (Spanish: Partido Acción Nacional, PAN) is a conservative political party in Mexico founded in 1939. It is one of the main political parties in the country, and, since the 1980s, has had success winning local, state, and national elections.

In the historic 2000 Mexican general election, PAN candidate Vicente Fox was elected president, the first time in 71 years that the Mexican presidency was not held by the traditional ruling party, the PRI. Six years later, PAN candidate Felipe Calderón succeeded Fox after winning the 2006 presidential election. In the 2006 legislative elections, the party won 207 out of 500 seats in the Chamber of Deputies and 52 out of 128 senators. In the 2012 legislative elections, the PAN won 38 seats in the Senate and 114 seats in the Chamber of Deputies, but the party did not win the presidential election in 2012, 2018, or 2024. The members of this party are colloquially called panistas.

General elections were held in Mexico on Sunday, 1 July 2012. Voters went to the polls to elect a new President of the Republic to serve a six-year term, replacing Felipe Calderón, 500 members of the Chamber of Deputies and 128 members of the Mexican Senate.

Several local ballots were held on the same day, including the election of a new Head of Government and new Legislative Assembly of the Federal District, gubernatorial elections in six states (Chiapas, Guanajuato, Jalisco, Morelos, Tabasco and Yucatán) and municipal and local congressional elections several states.

The Legislative Palace of San Lázaro (Spanish: Palacio Legislativo de San Lázaro) is the main seat of the legislative power of the Mexican government, being the permanent meeting place of the Chamber of Deputies, as well as the seat of the whole Congress of the Union, when the Chamber of Deputies convenes in conjunction with the Senate of the Republic. Built in the late 20th century after a 1977 political reform, the complex is located in Mexico City about a mile east of the Zócalo central square, in the Venustiano Carranza borough, next to the Palace of Federal Justice. The complex draws its name from its location, as the San Lázaro Railway Station was the former occupant of the grounds where the palace was built.