Nauru is a republic with a parliamentary system of government. The president is both head of state and head of government. A 19-member unicameral parliament is elected every three years.[30] The parliament elects the president from its members, and the president appoints a cabinet of five to six members.[31] Nauru does not have any formal structure for political parties, and candidates typically stand for office as independents; fifteen of the 19 members of the current Parliament are independents. Four parties that have been active in Nauruan politics are the Nauru Party, the Democratic Party, Nauru First, and the Centre Party. However, alliances within the government are often formed on the basis of extended family ties rather than party affiliation.