This NY Times article is worth a read. It notes,”Communists believed that organizing the working class would work only if white workers realized that their liberation, too, was bound up with the fate of black workers. Facing this threat, anti-Communists and segregationists worked hard to sustain the fractures. They blamed Communists for fomenting “race mixing,” evoking sexualized fears that social equality would mean black men having sex with white women….The party inspired loyalty for reasons beyond simply an affinity for Marxist ideas. It was the campaigns Communists ran against police brutality, the practice of lynching and the Jim Crow laws that made their politics relevant to the lives of ordinary people.”
You can read it in its entirety here.