In a federal system of government who elects the officials

The federal government of the United States (U. S. federal government) [a] is the national government of the United States, a federal republic in North America, composed of 50 states, a federal district, five major self-governing territories and several island possessions. The federal government is composed of three distinct branches: legislative, executive and judicial, whose powers are vested by the U. S. Constitution in the Congress, the president and the federal courts, respectively. The powers and duties of these branches are further defined by acts of Congress, including the creation of executive departments and courts inferior to the Supreme Court.