The organization of the Communist Party of the Soviet Union was based on the principles of democratic centralism. The governing body of the Communist Party of the Soviet Union (CPSU) was the Party Congress, which initially met annually but whose meetings became less frequent, particularly under Joseph Stalin (dominant from the late 1920s to 1953). Party Congresses would elect a Central Committee which, in turn, would elect a Politburo and a Secretariat. Under Stalin, the most powerful position in the party became the General Secretary, who was elected by the Politburo and Secretariat. In 1952 the title of General Secretary became First Secretary and the Politburo became the Presidium; the names reverted to their former forms under Leonid Brezhnev in 1966.