Politics of Bulgaria take place in a framework of a parliamentary representative democratic republic, whereby the Minister-Chairman is the head of government, and of a multi-party system. Executive power is exercised by the government. Legislative power is vested in both the government and the National Assembly. The Judiciary is independent of the executive and the legislature. Since 1990, Bulgaria has an unstable party system, nowadays dominated by the post-communist social democratic Bulgarian Socialist Party and several personalistic parties which emerge for a short period of time. The U.S. Freedom House considers Bulgaria a free country.