It's the Union Leaders, Stupid: Organized Labor's Failures in the South.

These historical actors and their scholarly champions suffer from what Goldfield aptly calls "the poverty of U.S. liberalism" (p. 34).[4] Liberal labor heads, many of whom were embedded in the political establishment, were exceptionally contemptuous of the Communist Party (CP), insisting that the organization did more harm than good. While many liberal scholars have described the New Deal state in a progressive light, noting its limited workplace-based protections and support for collective bargaining, Goldfield, an extraordinarily well-read Marxist, points out that the strongest unions, including the United Mine Workers, secured recognition from their stubborn bosses I before i the establishment of Section 7(a) of the National Industrial Recovery Act. Goldfield's point is critical, noting "the shallowness of those who have argued that it was the New Deal that was responsible for union organizing successes during the 1930s, rather than the workers themselves and their organizations" (p. 282). CP union activists were successful partially because of their commitment to racial equality, and Goldfield spotlights the importance of interracial solidarity and the Communist-aligned National Negro Congress (p. 138). [Extracted from the article]