The politics of Guyana takes place in a framework of a Parliamentary representative democratic republic, in which the President of Guyana is both head of state and head of government, and of a multi-party system. Executive power is exercised by the President and the Government. Legislative power is vested in both the President and the National Assembly of Guyana. Historically, politics are a source of tension in the country, and violent riots have often broken out during elections. During the 1970s and 1980s, the political landscape was dominated by the People's National Congress.