The constitution of 28 November 1966 established a unitary republic consisting of 26 (currently 29) provinces and a single National District. The government is effectively controlled by the chief executive, a president directly elected for a four-year term and eligible for reelection. Cabinet ministers (called secretaries of state) are appointed by the president, who must be at least 30 years of age.
The National Congress consists of a Senate, composed of 30 members, and a 149-member Chamber of Deputies, apportioned on the basis of population. Members of the two houses are elected for four-year terms and must be at least 25 years of age. Bills for legislative action may be introduced by the president, by the National Congress, or by the Supreme Court. Voting is by universal suffrage of citizens 18 years or older, although younger citizens, if married, may also vote. Presidential and congressional elections are not held simultaneously.