League. He kept on preaching that the discrimination and segregation in the south is against the principle from the bible. That's the reason why he was accepted by many white Americans too, esp, church leaders. His march to Washington had many white participants.
His contemporary black leader Malcolm was seldomly mentioned(who resorted to extreme black power slogan). And the most recent march to Washington by African American people (around 10 years ago) was not joined by one single white man.