I mentioned before that this campaign is playing out like a boxing match, with Obama appearing to have the upper hand, while McCain occasionally makes fairly significant attacks that have clear impact in the polls.
I just recalled (don't know why it took so long) Muhammed Ali's name for this strategy: rope a dope. Oddly enough, Andrew Sullivan used it in reference to Obama's strategy against both Hillary and McCain.
The way Ali always used it was to encourage his opponent to expend energy while he rested on the ropes. Then he would come back with an unexpected flurry of punches when the oppinent was at his weakest and end the fight.
Are we in the flurry stage? There are punches coming in from all sides, and the lead seems to be slacking.