section_path: Government and politics
section_name: Government and politics
paragraph_text: Government and politics
  
  The United Mexican States are a federation whose government is representative, democratic, and republican based on a presidential system according to the 1917 Constitution. The Constitution establishes three levels of government: the federal Union, the state governments, and the municipal governments.
  
  The federal legislature is the bicameral Congress of the Union, composed of the Senate of the Republic and the Chamber of Deputies. The Congress makes federal law, declares war, imposes taxes, approves the national budget and international treaties, and ratifies diplomatic appointments. The federal Congress, as well as the state legislatures, are elected by a system of parallel voting that includes plurality and proportional representation. The Chamber of Deputies has 500 deputies. Of these, 300 are elected by plurality vote in single-member districts (the federal electoral districts) and 200 are elected by proportional representation with closed party lists for which the country is divided into five electoral constituencies. The Senate comprises 128 senators: 64 (two for each state and two for Mexico City) are elected by plurality vote in pairs, 32 are the first minority or first-runner-up (one for each state and one for Mexico City), and 32 are elected by proportional representation from national closed party lists.
  
  The executive is the President of the United Mexican States, who is the head of state and government, as well as the commander-in-chief of the Mexican military forces. The President also appoints the Cabinet and other officers. The President is responsible for executing and enforcing the law and has the power to veto bills.
  
  The highest organ of the judicial branch of government is the Supreme Court of Justice, the national supreme court, which has eleven judges appointed by the President and approved by the Senate. The Supreme Court of Justice interprets laws and judges cases of federal competency. Other institutions of the judiciary are the Federal Electoral Tribunal, collegiate, unitary, and district tribunals, and the Council of the Federal Judiciary.
  
  Three parties have historically been the dominant parties in Mexican politics: the Institutional Revolutionary Party (PRI), a catch-all party and member of the Socialist International that was founded in 1929 to unite all the factions of the Mexican Revolution and held an almost hegemonic power in Mexican politics since then; the National Action Party (PAN), a conservative party founded in 1939 and belonging to the Christian Democrat Organization of America; and the Party of the Democratic Revolution (PRD) a left-wing party, founded in 1989 as the successor of the coalition of socialists and liberal parties.