The president has a huge racial gap to overcome in 2012. John McCain received 12% more of the white vote in 2008 than Obama. The gap was even larger among white men. McCain got 16% more of the white male vote in 2008 than Obama. The racial gap is much wider this year. White voters prefer Romney to Obama by 21%, and white males prefer Romney by 33%. Not all of this gap between the president and white voters is due to his race. George Bush got 17% more of the white vote when he ran against Kerry.
Minorities prefer Obama by much larger margins. They make up a smaller percentage of the voting population, however. This explains GOP efforts in many states to discourage minority voting.