In Communist states the presidium is the permanent committee of the legislative body, such as the Supreme Soviet in the USSR. The Presidium of the Supreme Soviet existed after 1936, when the Supreme Soviet of the USSR supplanted the Congress of Soviets of the USSR, as a replacement for the Central Executive Committee which was headed by "the Presidium of the Central Executive Committee". In its place was the Presidium of the Supreme Soviet alone, no Central Executive Committee, and from 1938 to 1989, the Chairman of the Presidium of the Supreme Soviet was the formal title of the head of state of the USSR until the office of Chairman of the Supreme Soviet was introduced in 1989, later to be replaced by the President of the Soviet Union in March 1990. The Republics of the Soviet Union were each led by Presidiums, such as the Presidium of the Supreme Soviet of the Russian Soviet Federative Socialist Republic and the Presidium of the Supreme Soviet of the Ukrainian Soviet Socialist Republic, whose chairmen were the "de facto" head of state in those republics.