São Tomé and Principe is governed under the constitution of 1990 . The president, who is head of state, is popularly elected for a five-year term and is eligible for a second term. The government is headed by a prime minister, who is nominated by the legislature and appointed by the president. The unicameral legislature consists of the 55-seat National Assembly, whose members are popularly elected for four-year terms. Administratively, the country is divided into the two provinces of São Tomé and Principe; Principe is autonomous.