Under the 1977 Constitution of the Union of Soviet Socialist Republics (USSR), the Chairman of the Council of Ministers was the head of government and the Chairman of the Presidium of the Supreme Soviet was the head of state. The office of the Chairman of the Council of Ministers was the equivalent to a First World Prime Minister, while the office of the Chairman of the Presidium was equivalent to the office of the President. In the Soviet Union's seventy-year history there was no official leader of the Soviet Union offices but a Soviet leader usually led the country through the office of the Premier and/or the office of the General Secretary of the Communist Party of the Soviet Union (CPSU). In the ideology of Vladimir Lenin the head of the Soviet state was a collegiate body of the vanguard party (see What Is to Be Done?).