I think there is nothing we can do, except for electing McCain.
The Dems are going to have 57 or 58 senators (can actually get 60, if everything goes right for them) and 255-180 (I hope not 270-165, but even this may happen) majority in the House. About what it was in 1993-94, before the Gingrich takeover.
GOP gained 54 seats in 1994 election, and now all these seats are coming back.
Even if Obama somehow manages to lose in November, all McCain will be able to do in the next 4 years is to veto some bills, and even some of these vetos will be overriden. Or he can simply go along and try to moderate the Rangel/Dingell/Pelosi-run Congress. And the GOP will still be percieved as being in power and get blamed for the economic troubles (which are pretty much given, for a decade or longer).
If Obama is elected, the Dems are on the clock. Who knows how much time they got? UK’s Labor is on its way out, but it took them 10+ years to self-destruct. The GOP here did it in 12. If the economy is lousy, the Dems may be on the way out in 2014. Maybe Obama will even lose reelection in 2012.
In any case, I don’t feel compelled to vote for McCain. Why waste GOP clock on somebody who is not even a Republican.