There is SOME truth in what you say. Clearly there are racists on the right, just like there are millions of blacks who wouldn't vote Republican if God was the GOP candidate. Prejudice is prejudice. It's stupid.
There is a BIGGER truth: most Republicans would have gladly supported a black, Rice or Powell for example.
What's going on is fear: fear that the Democrat machine in cohoots with a sympathetic press is taking the US in the wrong direction - the direction of Western Europe. This is aggravated by the perception (whether accurate or not) that Obama is an internationalist and a false Christian. His dismissive arrogance aggravates this.
For older Americans who remember, his documented association with one violent 60's anarchist and his hate spewing minister support this perception.
Personally, I think most of these concerns are misplaced. The press has always been bad. We have been charging into the 'Welfare State' for a generation. And ultimately Americans are conservative and will throw out the so-called 'progressives.'
When the left has no other excuse for this failed administration they play the race card. Fortunately more and more people are seeing through this excuse. More and more might even include a few 47%er who normally don't may much attention to this stuff (as long as theri government checks keep coming)