It'll be a few more days before we learn whether McCain-Palin are just riding a convention bounce or have changed the fundamental dynamics of the race. I think there's good reason to believe Palinmania will wear off and Obama will rise again. But it's got to be unnerving out in Chicago to see that a must-win state like Pennsylvania is creeping ever closer to a tie.

And here's the case for longer-term concern. It feels a bit as though Obama is out of steam, something that's happened before. The man needs big moments to rekindle his fire. Throughout the campaign, he's found those moments. His knockout Jefferson-Jackson performance in Iowa last December. That dazzling Kennedy family endorsement. Claiming the nomination on June 3. The unity event with Hillary. Invescopalooza. But what's left now? A killer debate performance, perhaps--but anyone who remembers last fall wouldn't bank on that (even if he did improve with time).

So what's left? I reiterate: Colin Powell. He could decide this election if he wanted to.

--Michael Crowley