Nothing to Contribute, but Everything to Learn
I think I've thought of another reason McCain is so eager to stop campaigning. I haven't heard anybody talk about his opportunity to learn about a critical issue in this campaign.
Think about it from a self proclaimed economic amateur's point of view. What do you do when you don't know much about the economy and you don't really know how the government does (or is supposed to) react to a financial crisis? What do you do when there is a sudden crisis in the economy and all of the questions you get asked on the campaign trail involve something you "know very little about"? When that crisis door opens and you realize you are falling in the polls because you have no good answers to any economic questions, you insist on postponing your beatings to go back to school. Where better to learn of the current crisis than in the negotiating rooms during the crisis? Even if you don't contribute to the discussion, you can finally have something to say to those pesky reporters who insist on doing their jobs.
John McCain is not just trying to avoid this week's debate on Foreign Policy, he knows the main focus of the debate will be on the economy. He knows he is lacking in both experience and wisdom on this issue and going to Washington to sit in on the conversation is his best opportunity for a cramming session before the big exam.