David Gergen flat out said it yesterday. When asked if it was a done deal that Obama would be President he said "No. Obama is black." (Paraphrased but that is very close.)
There may or may not be truth to the what Gergen is implying, but what he and all the others that bring up Obama's race as a possibility for his defeat fail to recognize, in their fervor to bemoan racisim, is that if Obama loses because of racisim, it will not be the racisim of the people to whom they so readily associate the trait, but to the others who they believe are free of it: Liberals and Moderates.
(Perhaps they do recognize it but don't want to go there)
A considerable majority of conservatives will not vote for Obama, and would not vote for him if he were white. So even if a portion of them are racists, his skin color makes no difference in their voting decision.
If he loses because of racisim, it will be because of the racisim of people who would have voted for him if he were white, but decided not to because he is black.
Of course I am hoping he loses for more important reasons, but watching Liberals blame racisim for his lose will make it that much more gratifying.