The Northern Marianas elect a governor and a legislature. The governor is elected for four year term by the people. The Northern Marianas Commonwealth Legislature has two chambers. The House of Representatives has 20 members (18 prior to 2007), elected for a two year term in single-seat constituencies. The Senate has 9 members, elected for a two year term in single-seat constituencies.The Northern Marianas has a multi-party system, with two or three strong parties and a third party that is electorally successful.