Following the German invasion of the USSR in 1941 he was assigned to the 'Initiative Group' parachuted into Poland in December 1941 to establish the Polish Workers Party (PPR). He headed the leadership troika with Bolesław Mołojec and Paweł Finder. The efforts to re-group the Polish communist movement achieved little and by autumn 1942 the organization was under severe pressure from the Gestapo.