Marc has a pre-debate run-down:

What resonates are moments -- the debate is taking place against the backdrop of a crisis, and it is the candidates' responses to the crisis, in real time, that will leave the most impressions.

The stakes are high for Obama here as well, but McCain is the one who's going to be defending his questionable choices of late.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.