At the moment, the GOP's week feels like an inversion of the Democrats' week in Denver. Sarah Palin's speech was a sensation on a level with Obama's triumph at Invesco. Just as the McCain campaign seemed at a loss for how to respond to Obama Thursday night, last night the Obama team lacked a killer comeback against  Palin (admittedly, responding to a winning speech is never easy).

McCain skilfully shifted the race's momentum the morning after Invesco with his surprise Palin announcement. Now, the question is whether the Obama team can continue the week-versus-week parallel and come up with a similar attention-getter. In the past, Obama's campaign has repeatedly demonstrated a marvelous sense of timing and an ability to rebound quickly after a setback. (As Jason Zengerle recently reported, for instance, Obama kept John Kerry's promised endorsement in his pocket and sprang it as a comeback after losing New Hampshire.)

I don't know what rabbit might be hiding in Obama's hat. But here's one fanciful thought: Colin Powell.

Imagine if Obama kicked off Friday with a Powell endorsement, shutting down the Palin hype and McCain speech bounce the same way as McCain smothered Obama's afterglow last weekend. After all, Bill Kristol recently predicted that Powell would actually appear at the Democratic convention. Clearly there's fear among Republicans that Powell will come out for Obama. And think about the impact a Powell endorsement would bring on the heels of a convention that is flogging McCain's military service, along with shots at Obama for never having worn a uniform.

Perhaps it's too much for Obamaphiles to hope for. Powell shot down the Kristol rumor and you get the sense the general is willing to stay neutral but not actively inflame the right.

Still, a Powell endorsement--be it Friday, or some other time later this fall--isn't unthinkable. And if delivered in the near future, it could deflate McCain's convention high in a single stroke.

--Michael Crowley