To me it's simple fact that a lot of the backlash against Obama is racist. I was raised in a Republican family (not all that bad 50 years ago), by parents who had been exposed to racism but were trying not to be influenced by it. I have to fight it myself.
Today's Republicans stand for rabid Christianity, sink-or-swim individuality, the intrinsic superiority of Americans regardless of what we do, and the dominance of the white culture.
Each of those characteristics can be positive when not taken to extreme: being religiously moral, competitive, patriotic, and proud of your culture are all good things. As such, the Reps can play on them, take them to extremes, and persuade their followers that they are being the 'good' people.
Obama has beena attacked on each one of these. He has been accused of being Muslim, socialist, not born a US citizen, and horror of horrors, he's black.
I don't think the Republican party is actually trying to do anything other than put itself back together. But it's managing to pull on the 'me first' survival mechanism of most of its members, who are overreacting in the way all humans do when they feel threatened.
And therefore, yes, I think it's mostly racial.