Pew put together an interesting review of polling in biracial elections, and the results are interesting. Through the ’80s and ’90s, polls tended to underestimate the ultimate vote for white candidates opposing black candidates. This suggests that poll respondents may have been acting more egalitarian than they really were. This wouldn’t be unheard of in polls; more people tend to claim they voted in previous elections than actually did.
What Pew found in 2006 is that polls in biracial campaigns tended to be much more accurate, that the hidden vote for the white candidate seems to have evaporated. It’s hard to be sure, but this suggests that some subset of voters who previously pledged support for black candidates but couldn’t bring themselves to actually cast that vote have changed their minds.
If true, this may indicate that racial categories have become less critical in how voters view candidates – a very good sign.