Politics of the Northern Mariana Islands takes place in a framework of a presidential representative democratic system, whereby the Governor is head of government, and of a pluriform multi-party system. The Northern Mariana Islands is an unincorporated territory of the United States, and in a political union with it in the form of a commonwealth. Executive power is exercised by the governor. Legislative power is vested in the two chambers of the legislature. The judiciary is independent of the executive and the legislature. Local government is carried out through three regional mayors.