# Chamber of Deputies (Mexico)

The Chamber of Deputies (Spanish: Cámara de Diputados, pronounced) is the lower house of the Congress of the Union, the bicameral parliament of Mexico. The other chamber is the Senate. The structure and responsibilities of both chambers of Congress are defined in Articles 50 to 70 of the Constitution.

## History

A bicameral legislature, including the Chamber of Deputies, was established on 4 October 1824. A unicameral congress existed from 7 September 1857 to 13 November 1874.

## Elections and qualifications
### Qualifications

Article 55 of the Mexican Constitution establishes the requirements to serve as a deputy. To be eligible, a candidate must:
* Be a Mexican citizen by birth with full legal rights.
* Be at least 18 years old on election day.
* Be a resident of, or have lived in, the state they seek to represent for at least six months prior to the election.
* Not be on active military duty or hold a police command within 90 days before the election.
* Not be a minister of any religious faith.
The article also imposes restrictions on public officials seeking election:
* Governors and the Head of Government of Mexico City cannot be elected as deputies in their respective jurisdictions during their terms, even if they resign.
* Ministers of the Supreme Court, magistrates or secretaries of the Electoral Tribunal of the Federal Judiciary, members of the General, local, or district councils of the National Electoral Institute (INE), or senior executives within INE must resign at least three years before the election.
* State secretaries, federal and local magistrates and judges, as well as municipal presidents and mayors in Mexico City, must resign at least 90 days before the election to be eligible.
* Officials holding leadership positions in autonomous constitutional bodies, as well as Secretaries or Undersecretaries of State and heads of decentralized or deconcentrated federal agencies, must also resign at least 90 days before the election.

### Elections

The Chamber of Deputies comprises one federal deputy (in Spanish: diputado federal) for approximately every 250,000 citizens. The Chamber has 500 members, elected using the parallel voting system.
Of the 500 deputies, 300 are elected by plurality from single-member districts, known as federal electoral districts, with each state having at least two districts, as stipulated in Articles 52 and 53 of the Constitution. The remaining 200 deputies are assigned through proportional representation across five multi-state, 40-seat electoral regions (circunscripciones), in accordance with Articles 53 and 54. These seats, not tied to specific districts, are distributed to parties based on their share of the vote within each electoral region, serving as a counterbalance to district-based representation. Deputies are elected alongside substitutes, known as alternates, making special elections rare.
Article 59 of the Mexican Constitution allows deputies to be reelected for up to three consecutive terms, but only for the party under which they were originally elected—unless they resign from the party before the midpoint of their term. From 1917 to 2015, a constitutional ban on immediate reelection required a complete renewal of the Chamber of Deputies at each election, making it one of the few legislative bodies in the world subject to complete renewal at each election.
Elections are held every three years. Congressional elections held midway through a six-year presidential term are referred to as midterm elections.

### Terms and reelection

Deputies serve three-year terms, beginning on 1 September following an election, with swearing-in typically occurring two to three days prior. Before 1933, terms lasted two years.

## Governing bodies
### Board of Directors

The Board of Directors oversees the sessions of the Chamber of Deputies, ensuring that debates, discussions, and votes comply with the Constitution and the law. It is elected during the constitutive session on August 29, three days before the start of the legislative term following an election. The Board consists of a President, four Vice Presidents, and seven Secretaries. The President of the Chamber of Deputies serves as the Chamber's highest authority and official representative, also assuming the role of President of the Congress of the Union during joint-sessions of the General Congress.
According to Article 17 of the Organic Law of the General Congress of the United Mexican States, each member of the Board is elected for a one-year term with the possibility of reelection. The Board is elected by a two-thirds majority, with candidates nominated by each parliamentary group.

### Political Coordination Board

The Political Coordination Board (JUCOPO) is the governing body responsible for facilitating political dialogue, negotiations, and consensus-building within the Chamber of Deputies, in accordance with Article 34 of the Organic Law of the General Congress of the United Mexican States. It promotes agreements among parliamentary groups to streamline the legislative process, oversees political debates, formulates the legislative agenda, and negotiates proposals and initiatives. Additionally, it manages the Chamber’s budget, allocates resources to parliamentary groups, proposes the composition of committees, and participates in the appointment process for autonomous bodies.
Article 31 states that the JUCOPO consists of the coordinators of each parliamentary group. The presidency is held for the full three-year term by the coordinator of the party with an absolute majority; if no party holds an absolute majority, the position rotates annually among the coordinators of the three largest parliamentary groups.

### Parliamentary groups

Article 27 of the Organic Law of the General Congress of the United Mexican States states that a parliamentary group consists of deputies organized according to their party affiliation. Each group must have at least five members, and only one group can exist per national political party with representation in the Chamber of Deputies. Each parliamentary group is led by a coordinator.

## Historical composition

This chart shows the historical composition of the Chamber of Deputies, from the 50th Congress to the present day.
Chamber of Deputies, 1976 to present :
| PCM  PAN  PRI  PARM  PPS  PST  PRT  PDM  PSUM  PMT  PFCRN  PMS  PRD  PVEM  PT  MC  PAS  PSN  PSD  PANAL  MORENA  PES | PCM  PAN  PRI  PARM  PPS  PST  PRT  PDM  PSUM  PMT  PFCRN  PMS  PRD  PVEM  PT  MC  PAS  PSN  PSD  PANAL  MORENA  PES | PCM  PAN  PRI  PARM  PPS  PST  PRT  PDM  PSUM  PMT  PFCRN  PMS  PRD  PVEM  PT  MC  PAS  PSN  PSD  PANAL  MORENA  PES | Total |
| 50th | 1976 | 10 12 195 20 | 237 |
| 51st | 1979 | 18 10 12 11 296 43 10 | 400 |
| 52nd | 1982 | 17 11 10 299 51 12 | 400 |
| 53rd | 1985 | 12 12 6 11 6 11 289 41 12 | 400 |
| 54th | 1988 | 19 50 33 36 262 100 | 500 |
| 55th | 1991 | 12 15 23 41 320 89 | 500 |
| 56th | 1994 | 10 71 300 119 | 500 |
| 57th | 1997 | 7 125 239 8 121 | 500 |
| 58th | 2000 | 8 50 3 3 211 17 206 2 | 500 |
| 59th | 2003 | 6 97 5 224 17 151 | 500 |
| 60th | 2006 | 15 127 4 16 106 17 206 9 | 500 |
| 61st | 2009 | 15 71 7 236 21 141 9 | 500 |
| 62nd | 2012 | 15 103 17 213 28 114 10 | 500 |
| 63rd | 2015 | 35 61 25 203 47 109 11 8 1 | 500 |
| 64th | 2018 | 61 191 21 27 45 16 81 2 56 | 500 |
| 65th | 2021 | 37 198 43 15 23 70 114 | 500 |
| 66th | 2024 | 51 236 77 1 27 35 72 1 | 500 |

## Latest election results and party standings

The current composition of the Chamber of Deputies:
| 49 | 253 | 62 | 27 | 37 | 71 | 1 |
| Party | Party | Single-member districts | Proportional representation | Total seats |
| | National Regeneration Movement | 176 | 77 | 253 |
| | National Action Party | 31 | 40 | 71 |
| | Ecologist Green Party of Mexico | 44 | 18 | 62 |
| | Labor Party | 36 | 13 | 49 |
| | Institutional Revolutionary Party | 11 | 26 | 37 |
| | Citizens' Movement | 1 | 26 | 27 |
| | Independent | 1 | – | 1 |
| Total | Total | 300 | 200 | 500 |