A member of the radical group within the Russian Social Democratic Labor Party , which, under Vladimir I. Lenin s leadership, staged the Bolshevik Revolution . The term bol shevik means a member of the majority bol shenstvo and was applied to the radical members of the Russian Social Democratic Labor Party after they won a majority of votes cast at a party congress in 1903. In March 1918, the Bolsheviks formed the Russian Communist Party Bolshevik and began calling themselves Communists. That party was the precursor of the Communist Party of the Soviet Union CPSU .
