If it is between Willard and Newt, Jonathan Chait, who writes very MEAN things, breaks down the choice for wingers:
"The robotic consistency of Romney's newfound conservatism does contrast sharply with Gingrich, who lurches between hysterical right-wing paranoia and bouts of bipartisanship. And yet the erratic character of Gingrich's swings suggests that they're unplanned, and thus that they spring from actual conviction, albeit momentary convictions. Gingrich actually believes what he is advocating at the moment he is advocating it. Nobody can plausibly say the same of Romney.
Romney is the handsome swindler who plots to win your mother's heart and make off with her fortune. Gingrich is like the husband who periodically gets drunk and runs off to spend a week with a stripper in a low-rent motel but always comes home in the end. Which one would you rather see your mother marry?"
Interpretation: Gingrich is a political sociopath and Romney has no soul. Take your pick.