The biggest obstacle to this scenario is, of course, President Obama, reinforced by the people around him. The Obamas have long regarded the Clintons as representing the tawdry side of politics: the deal-cutting, the calculating, the endless schmoozing, the permanent campaign — in short, the things that this professorial president could have used more of in his first term. The Clintons — Bill, at least — have tended to see Obama as politically naïve, steeped in youthful arrogance, a loner, happier to be right than successful. The mistrust may have abated a little, as Hillary has proved herself the most faithful of allies. And Bill has been a pretty disciplined defender of this administration, though his endorsements tend to come with a helping of paternalistic (and public) advice. But the Obamas and Clintons remain a marriage of convenience.

The Obama inner circle believes the president doesn’t need Hillary to win a second term. Just now, when the Republican field looks like a bug-spattered windshield and the most likely nominee strikes many in his own party as an empty suit, that confidence is understandable. But Democrats should not get too cocky. Mitt Romney, as I’ve argued before, has a case to make to voters and the resources to make it. In Iowa, exploiting the Supreme Court’s laissez-faire ruling on campaign spending, he brought down Newt Gingrich with an “independent” attack machine of considerable firepower.

Moreover, even if Obama can win without Hillary, there’s a lot to be said for running up the score. If she can do in 2012 what Obama did in 2008 — animate that feeling of historic possibility — the pair can lift some House and Senate candidates along with them.