I think a lot of the talk about the difference in voting behavior
by age cohorts (scroll down) has implicitly suggested that this was largely an age-race interaction. That is, older people are more likely to be, uh, discomfitted by an African-American president. I'd imagine that there was some of that, but I'd guess that the bigger effect was simply the age one. Obama actually didn't do too badly with seniors, and his attraction to young people, aside from the fact that they hate Republicans, was in part due to the fact that he seems like he has at least has one foot in the world they live in.
