Politics of Liberia takes place in a framework of a presidential representative democratic republic modeled on the government of the United States, whereby the President is the head of state and head of government; unlike the United States, however, Liberia is a unitary state as opposed to a federation and has a pluriform multi-party system rather than the two-party system that characterizes US politics. Executive power is exercised by the government. Legislative power is vested in both the government and the two chambers of the legislature.