He never stereotyped whites as a distinct singular identity that I can recall, it was always about their relation to maintaining inequality. One of his most impactful actions was convincing white and black unions to strike together, and that the fight for jobs and equality was one poor whites and blacks needed to share. In "The Other America" he constantly references poor white populations who share in the struggle.

MLK Jr never divided people by race like this, he thought that was one of the Three Evils plaguing American society.