About four years ago I described what I called the Republicans’ ‘bitch slap’ theory of electoral politics. Stuff like the Swift Boat attacks on John Kerry and McCain’s Celeb/P Diddy assault on Obama aren’t really about the attacks themselves. In themselves, they’re often too cartoonish to be believed in any literal sense. What they’re about is smacking the other guy around and making him take it. There’s no better way to demonstrate someone’s lack of toughness or strength than to attack them and show they are either unwilling or unable to defend themselves — thus the rough slang I used above. That not only makes the other guy look weak. It also transforms him into an object of contempt, which together are politically fatal. It’s this meta-message of weakness that resonates far beyond the literal claims. And it’s this that Democrats so often seem to miss — explaining the factual inaccuracies of the claims, demanding that the attacks stop, all the while reinforcing the intended message of the attacks in the first place.

You can even catch a hint of the mentality in the McCain camp’s huffing and puffing Thursday afternoon. The new and somewhat improbable line from the McCain camp is that they’ve actually been doing their best to go easy on Obama, to hold back the stuff that would really make him suffer. But now that Obama’s gone ahead and raised McCain’s inability to remember how many houses, now he’s really gonna get it with a super-mean Rezko ad and maybe even Reverend Wright. “He’s opened the door to this,” a McCain official told Marc Ambinder, in a campaign version of the wife-beater’s “You brought this on yourself!” As if McCain and his Rove lieutenants paid much mind to closed doors.

In effect, the devastating Rezko ad McCain says it never wanted to have to run is pretty weak. Which is pretty much what you’d expect for an ad put together in three or four hours by a campaign shell-shocked by a media firestorm they couldn’t put out by screaming POW, POW, POW.

What we’ll see now is whether Obama keeps McCain on the run with a continuing line of attacks or whether they’ll let up after this one reactive pick-up from McCain’s mistake. The House? gaffe exposes two of McCain’s biggest vulnerabilities — 1) the contrast between his old soldier pseudo-mystique and the pampered life he’s led for almost 40 years and 2) the age-related wobbliness which has his campaign aides keeping him largely off limits to the traveling press. These dovetail with his loose-cannon approach to critical foreign policy questions.

These issues — particularly 2 and 3 — are substantively critical issues. 1 is to the extent that it sheds light on McCain’s general ignorance and indifference to bread-n-butter economic issues and his willingness to flip between progressive and Bushite tax policy over the course of a couple years. But the tempo of this election and the fall out from the ‘celeb’ attacks will be determined in large part not by factual particulars but by whether Obama can show that when someone hits him hard he hits back twice as hard. Not cowering, ignoring or complaining. This is about the score and not the libretto.