The political system of Mexico is a federal republic, meaning it has a division of powers between the national government and individual states. It consists of three branches: the executive, led by the President, the legislative, which includes a bicameral Congress, and the judicial branch. The President serves a six-year term and cannot be re-elected. Elections in Mexico are held every three years for the Chamber of Deputies and every six years for the Senate. Political parties play a significant role, with major parties including the Institutional Revolutionary Party (PRI), the National Action Party (PAN), and the Party of the Democratic Revolution (PRD).