So, John McCain lives to fight another day. As GOP consultant Alex Castellanos put it on CNN, "John McCain could have lost this race tonight." Yes: A shaky performance after the last 72 hours of chaos might have created a sense that McCain was melting down. That didn't happen.

But McCain is losing this race by an apparently widening margin, and the debates offer his best chance to gain substantial ground on Obama. That didn't happen either. 

For one thing, McCain certainly benefited tonight from low expectations--expectations fueled in part by liberal critics who have caricatured him as a doddering old fool. He outperformed them easily.

McCain also had a clarity of message that Obama lacked. His core message is easy to sum up: Let's cut waste and spending. I'm a tough leader. Obama is naive and unprepared. Obama, by contrast, had no single message that he repeatedly drove home. He came across as sensible, studious, and thoughtful--but at times abstract and passionless. Obama did land some good shots at McCain's judgment over Iraq. But some of his other attacks--including his quips about McCain's "bomb Iran" song, and seemingly not wanting to meet with the president of Spain--seemed halfhearted, almost as though Obama was embarrassed to make them. (To his credit, perhaps.) I was almost reminded of Hillary's dead-on-arrival "change you can Xerox" crack from some primary debate 100 months ago.

And stylistically, McCain was more in control. He was the one setting the tone and introducing nettlesome topics, forcing Obama to respond and defend himself. Once or twice cut Obama off and talked over him, leaving Obama looking perhaps a little too polite. (Some TV commenters think McCain came across as rude, however, so maybe my read here is wrong, but I tend to think that voters respond to that kind of assertiveness in debates.)

But so what? Obama has a clear structural advantage in this race. His strategy over the past several days seems to be about laying low, appearing calm, cool and steady, and not taking any risks. Tonight was more of the same. And that was good enough. Should the race tighten in the coming days, Obama will have to put in a sharper performance in the next debate. But for now I'd guess he'll be sleeping soundly enough.

And before I neglect substance entirely: Nearly all of what we heard tonight was very familiar. Yet it was maddening to hear both candidates be so vague about both the financial crisis and about how they would modify their domestic agendas in response to any major bailout. And on a day when it appears US and Pakistani troops actually exchanged fire along the Afghanistan border, I also wish there had been a longer and tougher discussion of our policy there. But so it goes. 

Update: Different takes: Marc Ambinder says Obama won in a CBS poll among undecideds. Mark Halperin gives Obama a surprisingly clear victory.

--Michael Crowley