Actually, I thin their opposition to Obama is based in racism only on the part of a fairly small minority. But the corporatists, the "anti-government-ists," the "pro-lifers," the NRA crowd, and those who just plain want to retain or regain power for their party are eager to capitalize on that racism.   
They would be, I think, acting pretty much the same way if Hilary Clinton or Al Gore were in Obama's place. Look how much time & money they spent trying to get rid of or disempower Bill Clinton for 8 years.   (And let's not forget that when Clinton tried to use the CIA or the military to capture Bin Laden, the Republicans opposed that action, too - calling it "wag the dog.")