MEXICAN POLITICAL SYSTEM
Contents
What we now call Mexico - or, to give it its full name, the United Mexican States - was ruled by both the indigenous people and the Spanish conquerors in an authoritarian, hierarchical and centralised style which has had its impact on Mexican political institutions even today. Indeed, when the country first became independent in 1821, its first leader Agustín de Iturbide declared himself emperor. One infamous leader Porfirio Díaz managed to rule from 1884 to 1911.
As is the case with all nations, the constitution of Mexico reflects its history and the political system continues to evolve with current circumstances. However, given the turbulent history of the last 100 years and the present state of flux in domestic politics, this is especially true of Mexico.
Compared to the other nations of North America, Mexico is similar to the United States [click here] in having a presidential system with separation of the powers, but different from Canada [click here] which has a parliamentary system based on the British model. What is most different about Mexico, compared to both the USA and Canada, is that it has low levels of transparency and accountability and high levels of corruption and criminality. But, as this essay will make clear, in recent years there has been some progress in democratic consolidation.
Mexico achieved its independence in 1821 and has had several constitutions since then. The most durable constitution after the present one was that of 1857 which lasted until 1917. Following the Mexican Revolution of 1913-1916 and a social constitutional convention, the present constitution was adopted in 1917.
It can be argued that one of the principles that emerged from the revolutionary era represented by the 1917 constitution is the notion of 'constitutionalism', that is a legitimacy of and support for the fundamental principles of the constitution which is reflected in the popular culture. A notable illustration of this is that, in many Mexican cities (including the national capital), squares, streets and other features are named after the constitution itself or after notable articles of the constitution.
Articles which are particularly highlighted in this way are Article 3 on education, Article 27 on ownership of land and water, Article 123 on labour rights, and Article 130 on church restrictions.
A key principle of the constitution - set out in Article 83 - is that leaders should only rule for one term of six years. This was a reaction to the Portifirio Díaz rule of seven consecutive terms totalling 27 years and reflected the slogan of the 1911 revolution "Effective Suffrage and No-Reelection".
On the one hand, this rule can be seen as beneficial in that it prevents the sort of long-term, one-person rule that we have seen in many African and Asian countries. On the other hand, if a leader will never have to face re-election, there is little personal incentive to rule in a manner which attracts popular support (although, of course, there remains an incentive to use his power in a manner which is likely to result in his successor coming from the same political party).
A further complication of the 'six year rule' is that constitutionally it was only intended to apply to the executive (that is, the President) and not the legislature (that is, the Chamber of Deputies). However, in 1934, the rule was applied to Deputies as well, although qualified by the word 'consecutive'. Above all, this change weakened the legislature in relation to the executive as it is means that Deputies can build up limited experience and authority and gives the executive power over the nominees for congressional seats.
Furthermore, this rule has the perverse effect of making Deputies lacking in accountability, because they are not going to face re-election at the end of their term and possibly ever, and encouraging them to seek as much personal advantage as possible, since they are probably only going to have one opportunity to milk the system.
To make a change to the constitution requires the approval of both houses of the federal legislature and the approval of at least 17 of the 32 state legislatures. in fact, the Mexican constitution is the most amended in the world - more than 500 changes in just over 100 years.
Thanks in part to a constitutional amendment that set the goal of gender parity in all races for elected office and in appointments for top jobs in government, women now hold half the seats in Mexico’s congress and almost half the jobs in cabinet and one-third of the governorships. In 2023, Mexico’s Supreme Court ruled that prohibiting abortion was unconstitutional, but this has been slow to manifest in safe and accessible abortion at the state level.
The President of the United Mexican States - the proper name for Mexico - is the head of the state and the government, as well as the commander-in-chief of the Mexican military forces. The President appoints the Cabinet and other officers. The President is responsible for executing and enforcing the law, and has the power to veto bills. It is a powerful position.
Candidates for president must be at least 35 years old. They must be Mexican citizens by birth, as must one of their parents. They must have been residents of Mexico for at least 20 years. They also cannot have been either the governor of a state or the chief of government of Mexico City for six months prior to the election.
The President is elected for six years and can only serve one term. However, although this arrangement prevents self-perpetuating individual leaders, it has not stopped a self-perpetuating political leadership through the agency of one party so, for 71 years (1929-2000), the country was ruled by a succession of presidents from the same semi-authoritarian political party, the Institutional Revolutionary Party (PRI).
The last 11 presidents have been as follows:
The last presidential election was held on 2 June 2024. The winner, Claudia Sheinbaum, is a climate scientist and former mayor of Mexico City. She is the first female president of Mexico and won the presidency with 61% of the vote. She is the protege of the previous president, Andrés Manuel López Obrador who is popularly known as Amlo, and she ran for the party Amlo founded in 2014: the Movement for National Regeneration or Morena. She will take office on 1 October 2024.
It should be noted that Mexico does not have a vice-president. The constitution provides a process whereby, in the event that the presidency becomes vacant before the scheduled election, the Congress chooses a temporary president and then holds a new election.
The Mexican legislature is the bicameral Congress of the Union, composed of a lower house called the Chamber of Deputies and an upper house called the Senate of the Republic. The Congress makes federal law, declares war, imposes taxes, approves the national budget and international treaties, and ratifies diplomatic appointments.
The Chamber of Deputies
Originally the Chamber of Deputies consisted of 178 congressional districts each filled by plurality or majority vote. However, the semi-authoritarian Institutional Revolutionary Party (PRI) exercised such a tight grip on political expression and organisation that between 1949 and 1961 the PRI lost a mere 33 seats out of a total of 807 district contests.
In the face of increasing criticism of this political model, in 1964 the PRI decided to add additional seats based on the percentage of votes won by the opposition parties. Between 1964 and 1979, these extra seats numbered between 36-41. So the size of the chamber increased from 178 to 219. Most of these extra seats went to the National Action Party (PAN). The PRI introduced this change to create the impression that the electoral system was more democratic and competitive than was actually the case.
Then, in 1977, new legislation increased the number of district seats filled by majority vote from 178 to 300 and allocated 100 more seats to be allocated on the basis of the party's overall share of the vote in the election. So this time the Chamber increased from 219 to 400. Years later, the number of seats awarded through proportional representation went up from 100 to 200, making the total number of Deputies 500.
On the one hand, one could - and many Mexicans have - criticise this expansion in the Chamber of Deputies which represents an increase of 180% on the original size of the Chamber and makes it four times the size of the Senate. On the other hand, one could argue that the sizes of the two chambers are similar to the sizes of the two legislative chambers in the political system of the USA.
So today the Chamber of Deputies has 500 deputies. 300 deputies are elected in single-seat constituencies by plurality. The constituencies are divided among the 32 states based on population. The remaining 200 deputies are elected by proportional representation in five multi-state, 40-seat constituencies.
Elections to the Chamber of Deputies are held every three years, every second election coinciding with elections to the Senate and the Presidency. Nobody can serve more than two consecutive terms - totalling six years - as a Deputy. The last elections were held in 2024 and the next will be be held in 2027.
The Senate Of The Republic
The Chamber of Senators has 128 senators. 96 of these seats are in three-seat constituencies (corresponding to the nation's 31 states and Mexico City, the former Federal District which is the national capital). In these constituencies, two seats are awarded to the party with the most votes and one seat is awarded to the party with the second most votes. The remaining 32 seats are awarded by proportional representation on a nationwide basis.
Elections to the Senate are held every six years, each such election coinciding with the election to the Presidency. The last elections were held in 2024 and the next will be be held in 2030.
For many decades, there was growing concern that elections in Mexico were not free and fair. The Institutional Revolutionary Party (PRI) was accused of ballot-rigging and media manipulation.
The growing strength of the National Action Party (PAN) and the Party of the Democratic Revolution (PRD) in the congress led in the early 1990s to the creation of the Federal Electoral Institute and the Federal Electoral Court plus public funding for all political parties.
The Federal Electoral Institute was created in 1990 and in 2014 it was replaced by the National Electoral Institute (in Spanish, Instituto Nacional Electoral or INE). The INE is an autonomous, public organisation responsible for organising federal elections, that is, those related to the election of the President of the United Mexican States, the members of the Congress of the Union, as well as elections of authorities and representatives at local and state levels. In 1996, it achieved more independence when it became an agency outside government whose nine members are selected by Congress. The president is selected for a nine-year term and may not be reappointed.
The Electoral Tribunal of the Federal Judiciary (in Spanish, Tribunal Electoral del Poder Judicial de la Federación or TEPJF) was created in 1996. It is responsible for resolving disputes arising within federal elections and certifying the validity of those elections and hears appeals against the results of elections. Appeals may be lodged by candidates and parties.
There are three major political parties in Mexico.
MORENA
The name is an acronym for the Movimiento Regeneración Nacional (National Regeneration Movement). It has only been a political party since 2014, but it has been the ruling party of Mexico since 2018. It was formed by the last president of the country Andrés Manuel López Obrador. In the 2024 elections to the Chamber of Deputies, it won 42.4% of the votes and 248 seats.
The Institutional Revolutionary Party (PRI)
This was created in 1929 when it was called the National Revolutionary Party (PNR). It was formed at the initiative of Plutarco Elías Calles who was president from 1924-1928, but was concerned for the political stability of the nation when his elected successor (Álvaro Obregón) was assassinated before taking office. In 1938, the party changed its name to the Party of the Mexican Revolution (PRM). Then, in 1946, it adopted its third and current name, the Institutional Revolutionary Party (PRI).
Astonishingly in a so-called democracy, this one party won every state governor race until 1989, most seats in the Chamber of Deputies and the Senate until the 1990s, and all presidential elections until 2000. Although it failed to win the presidency in the elections of 2000 and 2006, it was successful in the presidential election of 2012. In the 2024 elections, it won 11.6% of the votes and 33 seats.
The National Action Party (PAN)
This party was founded in 1939 by dissident politicians from the Mexican government and other leading political activists searching for an ideological alternative to the then PNR (later PRM, now PRI). It grew very slowly under politically adverse circumstances at the state and local levels and did not make significant headway until the electoral reforms of 1964 which assigned a small number of 'party seats' to the opposition parties in the Chamber of Deputies.
Then the PAN managed to win the presidential elections of both 2000 and 2006. More recently, the successful PAN candidate in 2000 Vicente Fox backed the PRI presidential candidate in 2012 and was expelled from the party. In the 2024 elections, it won 17.6% of the votes and 68 seats.
For the 2024 elections, two major alliances were formed: the left-wing "Let's Keep Making History" and the opposition "Strength and Heart for Mexico". The first coalition is won a total of 373, seats which gives it a super-majority of two-thirds of the seats in Congress. This will allow the new president to pass legislation and budgets unopposed – and perhaps even change the constitution without the need for compromise.
The key organisations outside government that influence public policy in Mexico are as follows
The head of the Mexican judicial system is the Supreme Court of Justice. The court has 11 members who used to be nominated by the President and had to be approved by two-thirds of the Senate.
Each member of the court serves for a limit of 15 years or less if he or she reaches mandatory retirement age. A judge is not allowed to have held a public office one year prior to his or her service on the court.
Since the mid 1990s, the court has been able to rule on the constitutionality of laws.
On 1 June 2025, Mexico started to elect every judge in the country, from local magistrates to supreme court justices, by popular vote. It is a world-first democratic experiment, but one that has prompted warnings of low turnout, a political power grab and infiltration by organised crime.
The reform is the most radical move made by the governing Morena party and its allies since they won a congressional supermajority in 2024 allowing them to change the constitution at will. Few disagree that Mexico’s judicial system needs change. Justice is inaccessible to many, corruption is commonplace and impunity is rampant.
Morena claims its reform will address these issues by making the judiciary more responsive to popular opinion. However, critics say it will substantially undermine the separation of powers and that, by throwing the doors open to less qualified candidates whose campaigns may be backed by opaque interests including organised crime groups, it could aggravate the very problems it seeks to solve.
The Constitution of the United Mexican States provides that there will be three levels of government: federal, state and municipal. Below the federal level, there are 32 states (one of which is the capital Mexico City).
According to the constitution, all constituent states of the federation must have a government composed of three branches: the executive, represented by a governor and an appointed cabinet, the legislative branch constituted by a unicameral congress, and the judiciary.
Like the federal Congress, the state legislatures, are elected by a system of parallel voting that includes plurality and proportional representation.
Each municipality elects a mayor and this is the one exception in the Mexican political world where an office holder can run for a second term. Each term lasts three years so one person can serve two consecutive terms.
Each state has a local version of the Federal Electoral Institute that is responsible for all state and local elections.
Of the nine gubernatorial races in 2024, Morena held six and won the state of Yucatán, meaning it now controls 24 of Mexico’s 32 federal entities.
a name="Conclusion"> CONCLUSION
At one level, Mexico's political experience has been exceptional compared to the rest of Latin America (excluding Costa Rica) in that, since the 1950s, most other nations in the region have suffered military dictatorships or military control over civilian governments, but Mexico has managed to keep the military out of politics since the 1930s.
On the other hand, except for a very brief period in 1911, Mexico had no experience of competitive electoral politics for most of the 20th century, even while most other Latin American countries achieved electoral democracies by the 1980s.
In the last couple of decades, Mexico has shown itself capable of changing the political composition of its presidency through genuinely competitive elections, but the country is still in a process of democratic consolidation with much work still needing to be done to eliminate bribery and corruption and achieve full accountability and transparency. Mexican politics is a turbulent and personal affair and the political establishment does not easily respond to grass roots demands. As one Mexican put it to me on a visit to the country: "You need to be noisy to be heard".
Following the elections of 2024, Morena will hold more political power than any party since Mexico's transition to democracy in 2000. The peso slid against the dollar as investors reacted with jitters to Morena's projected hegemony.
In the recent presidential election, Claudia Sheinbaum presented herself as the continuity candidate and, now that she has been elected, voters will be looking to see how much she follows the policies of her mentor Andrés Manuel López Obrador. An immediate challenge is security: there are some 30,000 murders in Mexico each year and parts of the country are controlled by criminal gangs.
In terms of international relations, Mexico is always impacted by its big neighbour, the United States. The countries’ economies are deeply intertwined, with Mexico the top trading partner of the US. Mexico is also the immediate source of the fentanyl that kills 70,000 Americans a year, and a transit country for US-bound migrants, meaning that it always has the attention of US politicians.
ROGER DARLINGTON
Last modified on 31 May 2025
If you would like to comment on this essay e-mail me
For guides to the political systems of other nations click here