I agree with Ed that the debate expectations game is getting old. But here's an observation I don't believe is spin: President Obama has a lot more to lose than Romney in the debates. If the Obama campaign could, it would cancel the debates, which are shaping up as an excellent opportunity for Romney to do what he did so often in the primaries: use them to right a tottering campaign. The strategic question isn't really who is the best debater, but who has the most to gain and lose. On that question, the answer isn't really debatable: Romney.
Here is my worry if I'm the Obama campaign: My guy treats the debates as an annoying interruption to what has been a fairly charmed campaign so far. Rationally, the president knows how important the debates are, but he may also sense that there is no real benefit in them for him. It's a little like playing a big game when the other team has nothing to lose. If Romney scores a few points, Obama may sense an upset and it may make him timid or frustrated. The president has a streak of passivity when he doesn't see the upside.
If I were Obama's corner man, to wear out the sports analogies, I would try to get him to visualize the opportunity. He is poised to get something so rare in politics: a second chance. If he wins, it won't be with any of baggage of expectations that so weighed on his first term. Instead, he has a chance to be a better president in his next four years, to build on what he's done, to restore some comity to Washington, not by cooperating with people who will never compromise, but by beating them. It's kind of exciting when you think about it. And certainly worth fighting for.