Barack Obama may be the frontrunner in the Democratic race, but he lacks many things a frontrunner usually has: a substantive message beyond “new politics,” a record of accomplishment, and a dependable, broad-based core of support. What he does have may indeed already be dissipating. His rhetoric is growing stale. His attempts to remain above the fray have not worked, but he risks sullying his own image (and damaging his party’s chances in November) by getting into a mudfight with the Clintons.

Obama does still enjoy an advantage in delegates, as well as the benefits of an organization not rife with backbiting and dissension. But after weeks and weeks of cotton-candy rhetoric and press swooning, we’ve gotten down to the nub: all this froth has served to disguise a candidate who, on merit, is exceptionally vulnerable. It is only because his opponent is beset with personal deficits and organizational incompetence that it has taken so long for campaign watchers and voters to realize this. It’s difficult to maintain a candidacy that, at its core, is not honest with voters. Obama does not reach across the aisle (that’s the other nominee). He is not a “uniter” on policy. He is an unrepentant (and rather unimaginative) liberal. It’s hard enough to run as such when you have years of experience–look at John Kerry. But it’s infinitely harder when your public record is as thin as Obama’s.

Whether he pulls this out will have much to do, I suspect, with whether he can keep convincing voters that he offers a brilliantly new vision of politics. The fact is that he is new–but that he offers something deeply familiar.