The Philippines has a presidential system of government with executive power vested in the president, who serves a single six-year term. The legislative branch is composed of the House of Representatives and Senate. There is a system of checks and balances between the branches, including the ability of Congress to override presidential vetoes and impeach the president. Major political parties include the ruling PDP-Laban party, which follows democratic socialism, and the conservative Nationalist Party. Elections use a proportional representation system that includes party-list and single transferable voting. However, women remain underrepresented in formal political processes compared to men.