Marxist Obama can beat Socialist Romney.
Romney would not be able to run against Obamacare or even mention Obamacare in the debates. Doing so would make him look hypocritical.
Loss of credibility.
Hell, the Dems would be salivating over that race. Pitting their Justin Beiber in Chief against a guy who reminds everyone of a stereotypical politician/televangelist, it would sadly be a wipe out. Why do you think they don't say a word about Romney.