If 40% voted against, then a majority of Republicans surely voted against. But everyone tells there are no racists in the Republican Party!
No one is saying that the Republican Party is free of racists. Some Republicans are racist, but not a majority. Some Democrats are racist too (even some who voted for Obama). Some African-Americans would have voted against the amendment as well, though in much smaller numbers.
Another thing to remember is that old people are more likely to vote than younger people, skewing the results.