If we are to conquer racism, we must attack it - no matter which side of the racial divide. I have no doubt there are white voters who will not support a black candidate. That is racism. I also have no doubt there are balck voters who are attracted to Barack Obama's candidacy simply because he is black. That, too, is racism.
So racism is voting for people you have a cultural affinity with and against those you don't. In other words, it is another name for democracy.
There are actually few black voters who would always pick the black candidate against the white, and few whites who would always take the white against the black. If we had the immensely-entertaining-if-alarming prospect of an Alan Keyes vs. Dennis Kucinich race, I have no doubt that Mr. Keyes' support would be paler than Mr. Kucinich's.
However, let's not kid ourselves. Identity isn't the most important thing in politics. It's the only thing. Always has been, always will be, at least until the Son of Man returns in glory. Pronouncing those on the other side of whatever divides have become salient "racists" is psychologically satisfying, but ultimately stupid.