McCain needs to so dominate Obama that the electorate wonders how it could ever have considered the junior senator from Illinois presidential. Preferably Obama would either be left a blubbering mass or simply withdraw from the election in his closing statement.
Quite frankly that's too generous. I do not think there's a thing McCain could do in the third debate to reverse his descending fortunes. No matter which way he turns, he gets whacked. When he's nice, he gets whacked by supporters for being too nice. When he goes negative, his numbers go down.
Regaining McCain's lead is beyond his or his handlers' control at the point. It's in fate's hands. If there's an overwhelming bounce in the economy and the deregulation crowd lays claim to the moral high ground, he could bounce back. If there's a huge terrorist incident somewhere (which we all hope will not take place) and Americans' focus shifts to the international front, he could regain ground. But a stellar performance in the third debate? I doubt it!