How did Obama beat McCain's erratic grand-standing on the debate? By constantly standing up to him and turning his erratic stunt against him.
McCain said it was time to drop everything, including campaigning, and stay in Washington until a bail-out deal was done. Obama turned that argument back on McCain and said "Presidents need to be able to do more than one thing at a time." Note also how that line also cleverly, but indirectly, underscored the issue of McCain's age.
McCain said focusing on the economy meant the debate should be postponed. Obama turned that argument back on McCain and said that it was more important than ever for the public to hear from the two men who would be President.
Obama never wavered on his insistence that he would be in Mississippi to debate. Obama was constant where McCain was inconstant. And Obama applied jujitsu to all of McCain's arguments.
The result: McCain blinked. McCain had said "we must meet until this crisis is resolved" and his campaign would work "to delay Friday night's debate until we have taken action to address this crisis." And yet the crisis was not resolved when McCain was forced to flip-flop (again) and go to Mississippi with his tail between his legs.
McCain will no doubt grandstand throughout the debate. But Obama has already figured out how to beat the bully. Don't back down, and don't go on the defensive. That looks weak to the viewer because it is weak.
The best debate advice I can ever offer is the strategy that Obama already demonstrated here: The ideal response to any attack is to simply counterattack, ideally using your opponent's own words against him.
Since McCain holds both Obama and the truth in utter contempt, that should make winning the debate even easier. Jonathan Chait offers perhaps the definitive explanation in his New Republic piece, "Liar's Poker," for why McCain has fallen so low in his serial lying that his old friends don't recognize him and that even uber-deceiver Karl Rove thinks he has gone too far:
"The contempt that many McCain aides hold for Barack Obama," The Atlantic's Marc Ambinder wrote this summer, "rivals the contempt that McCain held for Mitt Romney a year ago." As Time reported, "McCain and his aides now view Obama with the same level of contempt they once reserved for tobacco-company executives, corrupt lawmakers and George W. Bush. They have convinced themselves that Obama is not honorable, that he does not love his country as much as himself."
The pattern here is perfectly clear. McCain has contempt for anybody who stands between him and the presidency. McCain views himself as the ultimate patriot. He loves his country so much that he cannot let it fall into the hands of an unworthy rival. (They all turn out to be unworthy.) Viewed in this way, doing whatever it takes to win is not an act of selfishness but an act of patriotism. McCain tells lies every day and authorizes lying on his behalf, and he probably knows it. But I would guess -- and, again, guessing is all we can do -- that in his mind he is acting honorably.
How do you deal with a man who things it is honorable to lie constantly?
Throughout the debate, Obama should calmly and repeatedly point out McCain's erratic, flip-flopping on the economy and his many incorrect domestic and foreign policy judgments. The point is not so much to get McCain to flare his well-known temper -- although that would be a nice side benefit. The point is to draw out of McCain as many of his now-standard lies as possible, since, as I've written, endlessly trumpeting those lies is the key to Obama's Can't-Lose Debate Strategy.
Obama does not need to respond to and debunk every McCain lie during the debate. Indeed, I'd suggest doing that only for a few of the biggest and most blatant whoppers. Obama really needs to be above the fray, not constantly calling McCain a liar, and certainly not getting into picky arguments about half truths and word choice. It is really the job of Obama's war room and his surrogates to list and repeat every one of McCain's lie.
The bottom line of winning campaigns never changes: If you aren't attacking, you're not winning.