20% non-Democrat or Republican is not the same as 4-5% who still have to make up their mind, or are actually considering two candidates. I used those different terms differently, so its not really changing a story
White guilt is not just sympathy for racism, like sympathy for a smear you mentioned above. white guilt is a feeling of general wrongdoing by caucasian americans for the mistreatment of african americans in the past.
the way racism will affect obama is different form the way white guilt might affect the election. Some point to racism as a bi-product of our natural generalization abilities, and our reverse rational in justifying them (if we are enslaving them we must be superior). I don't really want to get into explaining how some people believe actions and characteristics of individuals represent an entire "classification" or individuals, but white guilt is slightly more academic. While I'm sure there was some feeling of resentment and remorse in the caucasian american community (for actions committed by their ancestors against african americans) before the civil rights movement, there was serious consideration of reparation programmes once the point had been reached where the average sentiment was that african americans were on a level playing field but coincidentally weren't 'scoring goals' on that playing field. Instead of pointing to innate racism within our hiring practices and such actions from day to day, certain people in certain high places felt there was something still wrong with the legal/formal structure of our society that needed to be fixed. One of these reparation movements was the move toward affirmative action, which was still active at my alma mater until just recently. My home school is considered a "liberal" public university, and because affirmative action was enacted at other universities, places where new (one defintion of 'liberal') ideas arise, I will consider affirmative action a liberal policy. Coincidentally, I consider liberalism more in line with white guilt because liberals were more of a factor in pressing for civil rights for all americans in the 1960s, and, as I mentioned a few moments ago, certain individuals who drove the civil rights movement to fruition felt equality of status were necessary in addition to equality of opportunity.
I am not sure why racism is perceived more common among republican voters, or the "religious conservatives", but this group has not historically supported "white guilt" policies in law/policy making. Present-day "red states" have had past-day racist policies on the books and racist practices in their culture moreso than "blue states", so perhaps I do not need to discuss this point.
Couple the 4 or 5 percent who still might change their mind between now and the election, and the opinion that people do not hold a laundry list of rational explanations for the reason they support a candidate but rather anchor their reasoning onto certain character issues... I fear that judgement-tampering through deceptive or misleading ad campaigns could sway the outcome of an otherwise close election depending on the success of the non-principle non-issue campaign ads of the respective sides.
in my opinion...if one campaign has better ad writers supporting but not necessarily associated with, who write more sticky and contagious ads, that candidate will be successful in the end. the subject of those ad campaigns will boil down to race, I believe, because it is the most glaring and exploitable difference between the two candidates (exploitable via the two similar but different prejudices I've mentioned) and the election will be too close to avoid using these type of ad/rehtoric campaigns. fwiw
all of that comes from articles I can't publish here from my school library, cnn, and a few textbooks.
edit: with respect to the gallup poll... not that you or anyone else reading this thread is assuming the poll is "accurate", but to make the conclusion that the poll is "accurate" relies that people are aware of the prejudices that do and do not exist in their mind, aware of when to utilize them, and have the opportunity to turn them on/off when desired.