 The CPUSA 's membership peaked at around 80 @,@ 000 members during World War II under the leadership of Earl Browder , who was not a strict Stalinist and cooperated with the US government during the war . In late 1945 , hardliner William Z. Foster took over leadership of the CPUSA , and steered it on a course adhering to Stalin 's policies . The CPUSA was not very influential in American politics , and by 1948 its membership had declined to 60 @,@ 000 members . Truman did not feel that the CPUSA was a threat ( he dismissed it as a " non problem " ) yet he made the specter of communism a campaign issue during the 1948 election . 
