In 1933, along with Sidney Hook, Burnham helped to organize the American Workers Party led by the Dutch-born pacifist minister A. J. Muste. Burnham supported the 1934 merger with the Communist League of America which formed the US Workers Party. In 1935, he allied with the Trotskyist wing of that party and favored fusion with the Socialist Party of America. During this period, he became a friend to Leon Trotsky. Writing for "Partisan Review", Burnham was also an important influence on writers including Dwight Macdonald and Philip Rahv. However, Burnham's engagement with Trotskyism was short-lived: from 1937 a number of disagreements came to the fore.