While in Mexico, Trotsky also worked closely with James P. Cannon, Joseph Hansen, and Farrell Dobbs of the Socialist Workers Party of the United States, and other supporters. Cannon, a long-time leading member of the American communist movement, had supported Trotsky in the struggle against Stalinism since he had first read Trotsky's criticisms of the Soviet Union in 1928. Trotsky's critique of the Stalinist regime, though banned, was distributed to leaders of the Comintern. Among his other supporters was Chen Duxiu, founder of the Chinese Communist Party.