|Parliament name (generic / translated)
||Congreso de la Unión / Congress of the Union
|Structure of parliament
|Chamber name (generic / translated)
||Cámara de Senadores / Senate
|Related chamber (for bicameral parliaments)
Cámara de Diputados / Chamber of Deputies
||31 January 1917
Last amendment: 1996
|Mode of designation
||directly elected 128
||- 32 multimember (three seats each) constituencies corresponding to the 31 states and the federal district;
- a single national constituency for 32 seats.
Political parties submit a list of two candidates for each state;
Majority system: A total of 96 seats are filled by majority system, of which
- 64 seats are allocated to the two candidates receiving the largest amount of votes in each state;
- 32 seats are allocated to one candidate from the party which obtained the second largest amount of votes in each state (minority senators).
Proportional representation system:
- 32 seats are filled by a proportional representation system, based on party lists.
Voting is compulsory (no sanctions).
||- age: 18 years
- Mexican citizenship
- honest means of livelihood
- disqualifications: criminal conviction, imprisonment, fugitive from justice, sentence imposing suspension
||- qualified electors
- age: 25 years old on the day of the election;
- Mexican citizenship by birth;
- full possession of political rights;
- Six-month residence in the state where elections are held or in a neighbouring state.
||- Members and former members (having left the service less than 90 days prior to the elections) of the federal army, of the police or of the rural gendarmerie in the district where the elections are held;
- State secretary or sub-secretary, Justice of the national Supreme Court. However, secretaries resigning 90 days or more before the election and judges doing so two years before the elections are allowed to run for elections;
- State government secretaries, magistrates and federal or state judges. However, persons running for other jurisdictions or those resigning from their duties 90 days before the elections are allowed to run for elections;
- Ministers of any religious group;
- Former senators and deputies who served in the term immediately preceding the elections.
||- candidatures submitted by duly registered political parties.