A recent survey by the Pew Center indicates an accelerating polarization of American politics around race, summarized by Jonathan Chait in his ill-titled “This Statistic Shows the Republican Demographic Crisis Is Still Getting Worse.” The poll, based on likely voters in the 2014 elections, shows that non-White voters splitting 77-15 for Democrats, up 68-21 8 years ago. White voters split for Republicans 55-39 in 2014, but only 49-42 in 2006.
Based on the CNN exit polls, the disparities were actually greater in the 2012 presidential election, when Whites of all age groups and both sexes voted for Romney, and the White vote split as a whole split 59-39 for Romney. But in any case, the trend in three consecutive off-year elections is clear.
American politics has become racialized, with non-Whites being far more likely to vote as as a bloc than Whites. But Whites are catching up. I suspect that all the publicity given to the border surge and the promise of immigration amnesty will actually boost the Republican-Democrat split for Whites to be much higher than Pew predicts.