You are making a bad assumption that liberals aren't racists. The fact is, liberals are the biggest racists there are.
You can say that again, and one needs only to take a look in this opinion journal editorial
Yep, liberals are huge racists. That was brought home to me at a family gathering recently. I have a very, very liberal uncle, I’m talking way left (worked for the Jerry Brown for President campaign in the ‘70s) who has his nose out of joint because my cousin, his niece, is marrying a black man. And he didn’t mind telling me that, straight out. He just assumed I was a racist, too.
No question whom he’ll vote for in the election.