The party was founded by a group around Jacques de Kadt and Piet J. Schmidt on 28 March 1932.

The moderate leadership of the SDAP banned the publication, in reaction to this the leftwing opposition left the party.

The RSP was mainly supported by leftwing intellectuals and educated workers, who were highly concentrated in the large cities.

The party had a strong basis of young militants, united in Socialist Youth Union.

The OSP was shunned by other leftwing parties, because of its strong opposition to the social-democratic SDAP and the Communist CPH.