I think it has more to do with what Obama says about race. Or what Republicans are afraid he says about them and race. Every time he runs, they grab the nearest black conservative and throw him in front of the cameras as their proof that they aren't racist. Think Alan Keyes in '04, Michael Steele in '08 (they didn't have a black presidential candidate, so they settled for a black leader of their party), and now Herman Cain. None of these men were the best candidate for the jobs, but they were black and conservative, so they were called to duty.
Basically, without their realizing it, Barack Obama seems to have sold the GOP on affirmative action.