Congress of the Union

The Congress of the Union (Spanish: Congreso de la Unión), 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 consisting 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.

Congress of the Union

Congreso de la Unión
LXIV Legislature
Chamber of Deputies
FoundedSeptember 28, 1821 (1821-09-28)
President of the
Oscar Eduardo Ramírez Aguilar (MORENA)
since September 1, 2020 (2020-09-01)
President of the
Chamber of Deputies
Dulce María Sauri Riancho (PRI)
since September 3, 2020 (2020-09-03)
(500 Deputies)
(128 Senators)
Senate political groups
Government (78)
  •   MORENA (62)
  •   PVEM (6)
  •   PT (6)
  •   PES (4)

Opposition (50)

Chamber of Deputies political groups
Government (330)

Opposition (170)

AuthorityTitle III, Chapter II of the
Political Constitution of
the United Mexican States
Salary$500,000 pesos (Senator)[1][2]
$150,139 pesos (Deputy)[3][4]
Senate last election
July 1, 2018 (2018-07-01)
Chamber of Deputies last election
July 1, 2018 (2018-07-01)
Senate next election
July 7, 2024 (2024-07-07)
Chamber of Deputies next election
July 6, 2021 (2021-07-06)
La Patria Es Primero
(The Country Is First)
Meeting place
Senate Building
Mexico City
San Lazaro Building
Mexico City
Senate website
Chamber of Deputies website
Mexican Constitution of 1917
Reglamento para el Gobierno Interior del Congreso General de los Estados Unidos Mexicanos (Spanish)
San Lázaro Building, the Chamber of Deputies, Congress of the Union


The Congress is a bicameral body, consisting of two chambers: Senate of the Republic and the Chamber of Deputies. Its structure and responsibilities are defined in the Third Title, Second Chapter, Articles 50 to 79 of the 1917 Constitution. The upper chamber is the Senate, "Cámara de Senadores" or "Senado". It comprises 128 seats, 96 members are elected by direct popular vote for six-year terms; the other 32 seats are allocated based on proportional representation. The lower house is the Chamber of Deputies, or "Cámara de Diputados". It has 500 seats; 300 members are elected by popular vote to three-year terms, and the other 200 seats are allocated according to proportional representation.


The Congress of the Union (Congreso de la Unión) has two chambers. The Chamber of Deputies (Cámara de Diputados) has 500 members, each 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.[5] 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 to that rule. A party can lose only PR-seats by that rule (not plurality-seats). Also, a party cannot 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 Mexico City) and 32 by proportional representation on a nationwide basis.[6] In the state constituencies, two seats are awarded to the plurality winner and one to the first runner-up.


The powers allocated in the Congress are defined in article 73 of the Constitution. Among its powers, the Congress can admit new States into the Union, alter the allocation of powers granted to the federal government, lay and collect taxes, declare war (upon request of the Government), provide for and maintain the Union's armed forces, and coordinate economic activities.

Article 74, 75 and 76 of the Constitution state that each Chamber can address specific matters. In fact, some powers are reserved either to the Chamber of Deputies or to the Chamber of Senators, making the Congress of the union an imperfect bicameralism. For example, the former can approve the federal budget submitted by the Government, while the latter has the power to analyze the foreign policy of the Government, approve or dismiss the Presidential nominations of the Attorney General, Supreme Court Justices, diplomatic agents, general consuls, and senior civil and military officials.

Permanent Committee

The "Comisión Permanente del Congreso de la Unión", translated variously as the Permanent Committee or Standing Committee, is a body of 19 deputies and 18 senators that is responsible for tasks relating to the Congress when it is in recess.


It is conventional to refer to each Legislature by the Roman numeral of its term. Thus, the current Congress (whose term lasts from 2018 to 2021) is known as the "LXIV Legislature"; the previous Congress (whose term lasted from 2015 to 2018) was the "LXIII Legislature", and so forth. The I Legislature of Congress was the first Constituent congress after the 1857 Constitution.

Early in the 20th century, the revolutionary leader Francisco I. Madero popularized the slogan Sufragio Efectivo – no Reelección ("Effective suffrage, no reelection"). In keeping with that long-held principle, and until 2014, the 1917 Constitution stated that "Deputies and Senators could not be reelected for the next immediate term".[7]


On February 10, 2014, the Mexican Constitution was amended to allow reelection to the legislative bodies for the first time. Starting with the general election of 2018, deputies and senators are allowed to run for reelection.[8] Members of the Chamber of Deputies may serve up to four terms of three years each while members of the Senate may serve two terms of six years each; in total, members of both houses will be allowed to remain in office for a total of 12 years.[9]

Last election


Party Constituency Proportional Total
Votes % Seats Votes % Seats
National Regeneration Movement661,0681.18221,261,57737.501355New
National Action Party600,4231.0719,971,80417.59623 15
Institutional Revolutionary Party3,855,9846.8609,013,65815.90613 44
Party of the Democratic Revolution96,3930.1702,984,8615.2728 15
Citizens' Movement570,7741.0122,654,4524.6827 6
Ecologist Green Party1,198,0112.1302,528,1754.4627 3
Labor Party51,2600.0902,164,4423.8216 2
Social Encounter Party28,8780.0501,320,5592.3308New
New Alliance Party593,5071.0601,307,0152.3101 0
Independents1,109,1491.971,109,1491.970 0
Invalid/blank votes2,319,4894.122,344,3574.14
Registered voters/turnout89,994,03962.4989,994,03963.52
Source: INE

a Of the 53 seats won by the MORENA-PT–PES alliance, 40 were taken by MORENA, 8 by the PES, and 5 by the PT

b Of the 25 seats won by the PAN–PRD–MC alliance, 16 were taken by the PAN, 6 by the PRD, and 3 by the MC

c Of the 13 seats won by the PRI–PVEM–PNA alliance, 7 were taken by the PRI, 5 by the PVEM, and 1 by the PNA

Chamber of Deputies

Party District Proportional Total
Votes % Seats Votes % Seats
National Regeneration Movement709,8401.27820,972,57337.2584189 154
National Action Party697,5951.25510,096,58817.934183 25
Institutional Revolutionary Party4,351,8247.7819,310,52316.543845 158
Party of the Democratic Revolution124,8080.2202,967,9695.271221 35
Ecologist Green Party1,429,8022.5502,695,4054.791116 31
Citizens' Movement268,8760.4802,485,1984.411027 1
Labor Party67,4290.1202,211,7533.93461 55
New Alliance Party705,4321.2601,391,3762.4702 8
Social Encounter Party54,9060.1001,353,9412.40056 48
Independents539,3470.960539,3470.9600 1
Invalid/blank votes2,227,5733.982,242,6153.98
Registered voters/turnout89,994,03962.2089,994,03963.21
Source: INE

a Of the 210 seats won by the MORENA-PT–PES alliance, 97 were taken by MORENA, 57 by the PT, and 56 by the PES

b Of the 63 seats won by the PAN–PRD–MC alliance, 37 were taken by the PAN, 17 by the MC, and 9 by the PRD

c Of the 13 seats won by the PRI–PVEM–PNA alliance, 6 were taken by the PRI, 5 by the PVEM, and 2 by the PNA

See also


  1. "Manual de Percepciones de los Senadores..." (PDF). Senado de la República. p. 5. Retrieved 19 August 2011.[dead link]
  2. "2 Mil 312 Millones Para Sueldos de Senadores y Diputados en 2010". El Siglo de Torreón. Archived from the original on 29 June 2012. Retrieved 19 August 2011.
  3. "Poder Legislativo" (PDF). Cámara de Diputados. Archived from the original (PDF) on 3 December 2011. Retrieved 19 August 2011.
  4. "Consejeros del InfoDF ganan más que Ebrard". La Razón. Archived from the original on 19 August 2017. Retrieved 19 August 2018.
  5. "Archived copy". Archived from the original on 2011-08-23. Retrieved 2011-08-29.CS1 maint: archived copy as title (link)
  6. "Archived copy". Archived from the original on 2011-08-23. Retrieved 2011-08-29.CS1 maint: archived copy as title (link)
  7. Constitution of 1917, article 50, 59.
  8. "Constitución Política de los Estados Unidos Mexicanos. Artículo 59". Instituto de Investigaciones Jurídicas de la UNAM (in Spanish). Archived from the original on 14 October 2003. Retrieved 2 April 2015.
  9. Becerra, Bertha (20 May 2014). "Habría reelección de diputados y senadores a partir del 2018". La Prensa (in Spanish). Organización Editorial Mexicana. Retrieved 1 April 2015.