 His Lithuanian Popular Socialist Democratic Party (LSLDP) formed a block with the Peasant Union, another breakaway from LDP.Later in 1920, after an armed conflict between Poland and Lithuania erupted, Sleževičius was elected the chairman of the Lithuanian Defense Committee ("Vyriausias Lietuvos gynimo komitetas"), tasked with organizing and supporting the armed forces.Even without a position on the government, Sleževičius remained an influential politician.