List of leaders of the Soviet Union
Following Joseph Stalin's consolidation of power in the 1920s, the post of the General Secretary of the Central Committee of the Communist Party became synonymous with leader of the Soviet Union, because the post controlled both the Communist Party and the Soviet Government, both indirectly, via Party membership, and via the tradition of a single person holding two highest posts: in the Party and in the government. The post of the General Secretary was abolished in 1952 under Stalin and later re-established by Nikita Khrushchev under the name of First Secretary. In 1966, Leonid Brezhnev reverted the office title to its former name. Being the head of the Communist Party of the Soviet Union (CPSU), the office of the General Secretary was the highest in the Soviet Union until 1990. The post of General Secretary lacked clear guidelines of succession, so after the death or removal of a Soviet leader the successor usually needed the support of the Politburo, the Central Committee, or another government or party apparatus to both take and stay in power. The President of the Soviet Union, an office created in March 1990, replaced the General Secretary as the highest Soviet political office.
History of the French Communist Party
The first secretary-general of the PCF, Ludovic-Oscar Frossard, was often reluctant to obey the directives of the Communist International. Indeed, the party leadership was opposed to the strategy of the "proletarian unique front". Furthermore, one of Frossard's internal opponents, Boris Souvarine, was a member of the secretariat of the Communist International. Frossard resigned and left the PCF in 1923 to found a dissident United Communist Party which later became the Communist Socialist Party (but Frossard himself rejoined the SFIO). The general secretariat of the Party was shared by Louis Sellier (center faction) and Albert Treint (left-wing faction). At the same time, Boris Souvarine was expelled from the Communist International and the PCF due to his sympathy for Leon Trotsky.