The Supreme Soviet was the supreme organ of government power in the Soviet Union. Its members were elected for four-year terms. It in turn elected the Presidium, formed the Supreme Court, and appointed the Procurator General of the USSR. It comprised two houses, the Soviet of the Union, elected on the basis of population in political administrative units, and the Soviet of Nationalities, elected on the basis of ethnic populations. The Supreme Soviet convened regularly twice a year but could be called into extraordinary session by the Presidium or by demand of a union republic. The Presidium carried out the day to day operations of the Supreme Soviet when it was not in session. In actual practice, the Supreme Soviet served as a rubber stamp parliament for the Communist Party, where all real political and economic power resided.