aside from maybe a few pockets of the deep south; I think this issue looms larger in our minds than it does in reality.  The very same thing was said about Kennedy's Catholicism.  Alf Landon's defeat supposedly "proved" that fact for all time.  But when the election actually came, was it even a measurable factor?

Its a circular piece of thinking to to say "well America will never vote for a Black person because they are racist;  therefore we'd be foolish to put a black person forward as a candidate"

in other words, you won't know until you try.