The color of Barack Obama's skin is going to cost him votes. That, no one can deny. The question is, how many? A new AP/Yahoo poll figures it to be about 2 1/2 percentage points and goes further by suggesting a white version of Obama might earn as much as 6 percent more support.  The poll was conducted in cooperation with Stanford University and employed sophisticated techniques to screen out people's tendency to say what they think will make them look most noble. One of the most surprising results to me was the finding that 1/3 of white Democrats held negative opinions of black people and that age had very little bearing on those views. This Sunday Morning, I'll talk with St. Petersburg Times writer, Eric Deggans, Creative Loafing political editor, Wayne Garcia and political media consultant Renee Dabbs about the race factor in this presidential election.  That's at 11:00 am on ABC Action News this Sunday.