He joined the Communist Party of Germany in 1931 and in 1950 became a member of the central committee of the Socialist Unity Party of Germany and member of the Volkskammer. He was chairman of the council of ministers from 1963 to 1974 and again from 1976 until his resignation in 1989.
He was arrested for corruption in December 1989. In 1994 a court in Berlin decided that he should not get back his seized savings of 200,000 DM.