in 1931, wijnkoop initiated a proposal to combat the adverse effects of the economic crisis on the workers. however, the proposal was withdrawn in 1932. in 1907 wijnkoop founded, together with jan cornelis ceton and willem van ravesteyn, a magazine, called "the tribune". together, with the rest of the tribune group, he left the sdap and founded the social democratic party, which in 1919 changed its name to communist party of holland, or the cph.