The Communist League of America (CLA) was formed in 1928 by American communists who sympathized with the Left Opposition (LO) in the USSR. Some of them had left or had been thrown out of the Communist Party USA (CPUSA) for this, including the CPUSA chairman, James Cannon, the CPUSA branding this sympathy Trotskyism. Many of them had been involved in the CPUSA-affiliated legal organization, International Labor Defense. They began publishing a newspaper called The Militant, which originally was aimed at influencing members of the CPUSA. Their youth organization was the Spartacus Youth League. It was founded by James P. Cannon, Max Shachtman and Martin Abern in 1928
In 1934, the Communist League of America (CLA) was looking for subjectively revolutionary elements who were organizing outside the CPUSA that they could join forces with. One such organization was the American Workers Party (AWP). The AWP had just been active in the successful Toledo Auto-lite strike, whereas the CLA had recently been active in the successful Minneapolis Teamsters Strike. The AWP and CLA merged in December of 1934 and formed the Workers Party of the United States.
The CLA retained connections with Leon Trotsky's International Left Opposition and after their expulsion, initially positioned themselves as not a rival party to the CPUSA, but as a faction of it and the Comintern. The group published The Militant as its regular newspaper.
The group soon became known simply as the Communist League of America. As the CPUSA and the Comintern became increasingly Stalinized the tactic of acting as an external faction of the Communist Party was replaced with plans to create the Fourth International as a new revolutionary international to replace the Third International and to replace the Communist Party with a new mass workers party.
Local leaders associated with the Communist League of America led the Minneapolis Teamsters Strike of 1934. The strike paved the way for the organization of over-the-road drivers and the growth of the Teamsters union. It, along with the 1934 West Coast Longshore Strike (led by the Communist Party USA) and the 1934 Toledo Auto-Lite Strike led by the American Workers Party, were important catalysts for the rise of industrial unionism in the 1930s, much of which was organized through the Congress of Industrial Organizations.
In 1934, the CLA merged with A. J. Muste's American Workers Party to form the Workers Party of the United States. In 1936, the new party negotiated a fusion with the Socialist Party of America, however, the CLA continued to exist as an independent tendency and continued publishing their own newspaper, Socialist Appeal.
The Trotskyists success in recruiting a large number of members to the Socialist Party's youth wing, the Young People's Socialist League, concerned Norman Thomas to the degree that he decided to expel the CLA from the Socialist Party in 1937. However, the CLA was able to win most members of the YPSL and split them from the Socialist Party.
The enlarged group held a convention on January 1, 1938 to launch the CLA's successor, the Socialist Workers Party. Later that year the Fourth International was formally launched.
- Communist League of America (Opposition) (1929 - 1934). Online documents from Early American Marxism archive. Retrieved August 23, 2006.