I think that you are touching on one of the flaws of classic socialist theory, namely the reduction of race (gender, sexual orientation, etc) to the epiphenomenal status, with class being primary. It simply does not work like this. And it is not solely an American problem. The same was true in apartheid South Africa. In that instant, they actually stunted the countries economic growth because it would have necessitated greater incorporation of blacks into the economy in non-menial positions.
Poor whites in this country constantly act against their interest because of their identification with white elites who really could care less about them. The elites are doing the same thing with respect to matters such as gay marriage, abortion, and teaching evolution in the schools. The corporate elite trot out these social conservative platforms to mobilize poor and working class whites, when their real agenda is filling their pockets.