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The Socialist Workers Party was founded in 1938 from a split in the Socialist Party of the USA. They were supporters of Leon Trotsky's theories and expected that after WWII there would be Communist revolutions throughout Europe and the U.S. When strikes did not lead to revolution in the United States, the Socialist Workers Party started to look for explanations. In 1946 they published a pamphlet called Build a Labor Party Now, which argued that successful strikes were no longer enough to spark real change, since the government was fighting against labor. Their solution was to call on their supporters to form a political party to take control of the government.
Sources: Clark, G. (1946). Build a Labor Party Now. New York, NY: Pioneer Publishers.