The Communist Party of the Soviet Union (, ), abbreviated in English as CPSU, was the founding and ruling political party of the Union of Soviet Socialist Republics (USSR). The CPSU was the sole governing party of the Soviet Union until 1990 when the Supreme Soviet annulled the law which granted the CPSU a monopoly over the political system. The party was founded in 1912 by the Bolsheviks (the majority faction of the Russian Social Democratic Labour Party), a revolutionary group led by Vladimir Lenin which seized power in the aftermath of the October Revolution of 1917. The party was dissolved on 29 August 1991 soon after a failed coup d'état.