Nearly one in five Republicans opposes interracial dating, compared to just one in 20 Democrats. For the record, I think that disapproval of black-white interracial dating is actually higher than what people are willing to admit when polled. We can see this in their behavior on dating sites. Republicans are largely white, and we have good data on how whites respond to black profiles and messages.
This is part of a broader difference in racial attitudes
A poll conducted by the Associated Press before the 2012 election found that 79 percent of Republicans agreed with negative statements about racial minorities, such as “If blacks would only try harder, they could be just as well off as whites.” Among Democrats, the figure was just 32 percent. [WaPo Wonkblog]