In the 1966 elections, the Social Democrats and the SF won a combined majority in parliament, in which the SF doubled its number of seats from 10 to 20. A Social Democrat minority government was formed, which was supported by the SF. The cooperation lasted only one year, but lead to considerable conflict within the SF: in 1967 the Left Socialists (VS) broke away from the SF. In the subsequent 1968 elections, the SF lost nine seats and the VS entered parliament with four. In 1969 the party chairperson Larsen stood down, he was replaced by Sigurd Ømann.