Irving Howe says that the Communists used "Shock troops, a sort of paramilitary vanguard handy with knives, belts, pikes.

"[1][additional citation(s) needed] The most active radical and long-time Communist Ben Gold, was president from 1935 until he was forced out by moderates in the 1940s.

In 1937, the IFLWU left the AFL and joined the new Congress of Industrial Organizations (CIO), led by John L. Lewis.

In 1948, former CIO general counsel Lee Pressman joined Joseph Forer, a Washington-based attorney, in representing Irving Potash, vice president of the Fur and Leather Workers Union along with four others (Gerhard Eisler, supposedly the top Soviet agent in America; Ferdinand C. Smith, secretary of the National Maritime Union; Charles A. Doyle of the Gas, Coke and Chemical Workers Union, and John Williamson, labor secretary of the Communist Party USA).

[2] Between 1949 and 1950, with Cold War tensions rising, the CIO expelled the IFLWU and 10 other unions that it accused of being "communist dominated."