Count me among those who find Barack Obama's sudden burst of concern over Social Security to be a bit of an irritating pander. But more than that, it's a sign of the campaign's absence of options. No one really thinks "straight talk" on pension spending will win Obama the primary. Paul Tsongas tried that, and it failed then, too. Bob Kerrey tried something similar, and it was also unsuccessful. Offering to give people their medicine on fake entitlement crises isn't that impressive. And that's not even getting into the fact that if Obama were really concerned with spending, he wouldn't have proposed a health care plan without really meaningful cost control mechanisms. (Obama's plan, like that of the other Democrats, will help control costs down the road, but it doesn't, in the short-term, impose global budgets, large scale negotiations, massive cost sharing, or anything else that will hugely change spending growth. It's politically feasible, but not the "straight talk" he's basing this Social Security argument on.)

But Obama's out of differences. He failed to define Hillary Clinton on Iraq, and failed to offer a total withdrawal plan he could use to draw distinctions. He failed to come out with a health care plan even as ambitious as Hillary's and Edwards'. He failed to come out with a far-reaching tax plan that could undergird an economic policy. And since there's nothing tangible he can point to where he's the progressive and she's not -- and since she's been quite skilled at fuzzing her differences on Iraq and Iran -- he's got no case to make. The "I'm more honest about entitlement spending" is something of a final shot, though not a very strong one.

Some of this, to be sure, isn't Obama's fault. Clinton has run a really good campaign. The other day, I was trying to think of how, were I in a rival campaign, I'd try and attack it. And I came up with, basically, nothing. I know policy areas where I, using my secret-DC-decoder-ring, think she's weak, but not where I'd be able to make that case to the public. The amount of money she takes from lobbyists -- which Edwards gave a blistering speech about yesterday -- is the only vulnerability I could think of. Indeed, I sort of think Hillary isn't very vulnerable to anything but a massive attack, and that Obama is actually just hoping Edwards takes her out, as Gephardt did Dean in 2004.

--Ezra Klein