Obama wasn't close to his best tonight. He was much less crisp and coherent than last week, and generally looked a little fried. Like several of my colleagues, I thought his critique of McCain's health care plan was especially convoluted. All he needed to say was that lots of people would lose employer-based coverage under McCain's plan, and that McCain's $5,000 tax credit wouldn't offset the $12,000 their current plans are worth. Instead Obama threw in a digression about taxing health benefits, which, while true, had nothing to do with the thrust of his response.

Obama also missed a few easy comebacks, as when McCain bristled at Rep. John Lewis's recent comments, which included a (slightly) over-the-top allusion to George Wallace. Obama should have immediately rejected the Wallace analogy; instead, he riffed about how most voters think McCain's running a more negative campaign. Again, that's true enough. But it lacked the emotional punch of a pithy disavowal (which only came after McCain doubled-back to Lewis's comments).

Having said that, Obama was coherent enough when he had to be. His response to the Ayers charge--including a recitation of all the Republicans who served with him and Ayers on that infamous board--should defuse the issue once and for all. And, as was the case last week, tonight left little doubt that he plans to cut taxes for 95 percent of workers.  

More to the point, Obama was much, much more coherent than McCain, who stopped and started and bobbed and weaved so jarringly he looked like a running back evading a swarming defense (often unsuccessfully). Take, for example, McCain's various pleas on behalf of that newly-minted celebrity, Joe the Plumber:

You were going to put him in a higher tax bracket which was going to increase his taxes, which was going to cause him not to be able to employ people, which Joe was trying to realize the American dream.

And later:

Now, Joe, Sen. Obama's plan, if you're a small business and you are able -- and your -- the guy that sells to you will not have his capital gains tax increase, which Sen. Obama wants, if you're out there, my friend, and you've got employees, and you've got kids, if you don't get -- adopt the health care plan that Sen. Obama mandates, he's going to fine you.

Huh? And that's without the various ticks and jerks that accompanied McCain's delivery.

Beyond garden-variety incoherence, McCain had three problems I could detect. First, he had a way of turning talking points into complete non sequiturs by slapping them on the end of unrelated answers. My favorite came at the end of his second pass at Ayers and ACORN, when he added, hopefully: "[M]y campaign is about getting this economy back on track, about creating jobs, about a brighter future for America." Riiiight. Later, McCain appended this to his critique of Joe Biden's foreign-policy judgment: "I want to come back to, notice every time Sen. Obama says, 'We need to spend more, we need to spend more, that's the answer' -- why do we always have to spend more?" I realize the predicate doesn't always have to follow from the subject, but shouldn't it at least be in the same ballpark?

Second problem: McCain has a habit of making jokes and allusions no one else catches; tonight he really outdid himself. At one point Obama used Joe the Plumber to make a point about his health care plan. In response to which McCain blurted out: "Hey, Joe, you're rich, congratulations." Weird stuff. McCain also repeatedly invoked Obama's line about "spreading the wealth around" without explaining what makes it so offensive (beyond his own menacing tone). It didn't strike me as self-evidently damning.

But, as in previous debates, McCain's most glaring defect was his persistent sneering and dismissiveness. Here's McCain on the Colombia trade deal: "Free trade with Colombia is something that's a no-brainer. But maybe you ought to travel down there and visit them and maybe you could understand it a lot better." McCain's take on equal pay for equal work (in its entirety): "Obviously, that law waved the statute of limitations, which you could have gone back 20 or 30 years. It was a trial lawyer's dream." McCain on a health exception to abortion restrictions (again, in its entirety): "He's [for] health for the mother. You know, that's been stretched by the pro-abortion movement in America to mean almost anything. That's the extreme pro-abortion position, quote, 'health.'" Yikes.

I even thought Obama got the better of the moment the pundits deemed McCain's finest--his rejection of the link between him and George Bush. "Senator Obama, I am not President Bush. If you wanted to run against President Bush, you should have run four years ago." It was fine as one-liners go. But, in response, Obama was both magnanimous and devastating. He praised McCain for occasionally breaking with his party on an issue like torture, then lacerated him for hugging Bush on the issues people care most about. "But when it comes to economic policies," Obama said, "essentially what you're proposing is eight more years of the same thing. And it hasn't worked."

That, for me, was the debate in a nutshell: McCain fuliminating angrily, if sometimes effectively; Obama yielding more than he should at times, but still deadly on bottom-line differences. The election obviously isn't over. But McCain came up empty on his last, best chance.

--Noam Scheiber