Austria is governed under the constitution of 1920 as revised in 1929, and has a mixed presidential-parliamentary form of government. The president, who is the head of state, is elected by popular vote for a six-year term and nominates the chancellor (prime minister) and confirms the cabinet. The chancellor, who is head of government, heads the cabinet, which is responsible to the house of representatives ( Nationalrat ) of parliament. The House of Representatives is popularly elected according to proportional representation. The upper house of parliament, the Senate ( Bundesrat ), is chosen by the provincial assemblies. Administratively, Austria is divided into nine states.