Newt Gingrich may, to some, seem a loathsome creature, but you gotta admit he has perseverance. The roly-poly former speaker has absorbed attacks, both personal and political, that would have reduced most pols to the fetal position. But his remarkable combination of grandiosity, self-delusion, and brazen, utter, shameless chutzpah keeps him coming back.

Then again, the quality of the shots taken at him have not always been that impressive. It says something, perhaps, about the Republican presidential field that Michele Bachmann was the only candidate with the cojones to land a direct hit on Gingrich in the Sioux City, Iowa, debate.

Mitt Romney, who has reverted to the not-a-follicle-out-of-place hairstyle, never really got up the gumption to hit Newt. Not the way he had hit Rick Perry when Perry was ascendant.

If Romney tended to pull his punches, Bachmann threw haymakers. She scorned Gingrich’s influence-peddling, hammering his tenure as a paid consultant for Freddie Mac’s lobbyists. (Full disclosure: I consulted for Freddie’s PR shop, which was based in Virginia; the lobbying office for which Newt worked was in downtown D.C.) Bachmann’s contempt was withering. Newt’s defense was pitiful. And at the end of the debate she was still hammering Newt, raining scorn (and right hooks) on the former speaker’s record on social issues. Bachmann is the only one who put Newt on the canvas.

But it was a knockdown, not a knockout. Gingrich regained his footing quickly, demagoguing the federal courts in a way that would have made George Corley Wallace proud. He called federal courts “dictatorial” and defended a plan to haul federal judges before Congress and abolish the entire Ninth Circuit Court of Appeals.

As Gingrich roared back, Romney faded. Romney doesn’t need to win Iowa, so perhaps he’s writing it off. But then why is he spending time and money there? It has to be enormously frustrating for Mitt. He has been running almost nonstop for four years, spent untold millions, given hundreds of speeches, run ads, made Web videos, attended town-hall meetings and editorial boards and interest group meetings—and he’s gone from 25 percent in Iowa in 2007 to 17 percent today. Face it, Mitt: if you were the president of one of those companies you bought, you’d have laid yourself off by now.

This is the last scheduled debate before the Iowa caucuses and the New Hampshire primary. From here on in it’s the ad wars and ground wars. Romney and Perry and Paul will hammer Gingrich in what I hope will be brutal attack ads, while Bachmann and Santorum and Paul (again) will use their organizations to undermine Newt. It is certain to have an effect.

But it is telling that the man who dispatched Rick Perry with such skill and strength has chosen to shrink from confronting a doughy 68-year-old grandfather. He could take lessons in toughness from Bachmann.