In a recent study of young white women, researchers found that subjects were more likely to plan to vote for Obama for president if asked around the time when they were ovulating. This was only true, however, if the women perceived Obama to be lighter-skinned than he actually is. If they perceived him to be darker than he is, closeness to ovulation lowered the chance of voting for him.
The authors interpreted this to mean that women become sensitive to men as potential mates around the time when they are most fertile; if a man seems dangerous (in this study blackness is thought to be associated with dangerousness) they are repelled by him out of fear of sexual assault; if a man seems powerful, attractive, and safe, they will be attracted to him. The study also found that these tendencies were particularly strong among conservative women (liberal women planned to vote for Obama, regardless).
The authors also suggest that, since Obama won the election, many whites do not perceive him as black. They imply that people look at more than skin color when determining race, and Obama's education, career, demeanor, Waspishness, and restraint communicate whiteness.
The message here for Republicans for 2012 is that a few percentage points might be gained among women if the nominee is a powerful, attractive yet safe candidate. Of the current prospective men, I suspect that Romney best fits the description, which is not saying much. Most of the candidates seem weak or unattractive: politics attracts many weasels.