Who is the antagonist in Black No More by George S. Schuyler?

In a novel explicitly about race and America's race problem, racism is an important and central theme here. There are two key racist organizations in the book, the Knights of Nordica and the Anglo-Saxon Association of America, and both are white supremacist groups that believe that black people are not equal to white people and that black and white people should not marry because such marriages result in biracial children who make the white race less pure.