12/15/2011 11:41 am ET Updated Dec 15, 2011

Newt Gingrich Gets A Last Go-Around In Final Pre-Caucus Debate

DES MOINES, Iowa -- Newt Gingrich swaggers into the final Republican primary debate before the

Jan. 3 Iowa caucuses still leading in the polls, but there are signs that his momentum is waning.

Gingrich, the former House Speaker from Georgia, shined in the last debate just five days ago, capping off a momentous two-week period for him in which he soared to a commanding lead in national polls and in surveys of key early primary states, putting former Massachusetts Gov. Mitt Romney in a vulnerable position for probably the first time this entire electoral season.

But over the last few days, Gingrich has suffered multiple small puncture wounds. His polling numbers have sagged. His negative numbers have risen. Much of the public discussion about Gingrich's candidacy has focused on his controversial statements, such as the Palestinian people being "invented" and having children in low-income neighborhoods clean the bathrooms in their schools to make money.

Gingrich was forced to fire a campaign staffer in Iowa who called Mormonism a "cult" (though some might argue that might be a dog whistle for some very conservative evangelicals). He has also taken a beating from conservative opinion makers and elites, some of whom have united around Romney.

The website for National Review, one of the foremost conservative magazines, put a picture of Gingrich on its front page -- under the headline, "Against Gingrich."

"His character flaws -- his impulsiveness, his grandiosity, his weakness for half-baked (and not especially conservative) ideas -- made him a poor Speaker of the House," the National Review editors wrote, taking an official position against Gingrich without actually endorsing Romney or anyone else.

"Again and again he combined incendiary rhetoric with irresolute action, bringing Republicans all the political costs of a hardline position without actually taking one. Again and again he put his own interests above those of the causes he championed in public," National Review wrote.

Most importantly, however, Gingrich has failed to mount much of a response to the brutal punishment he is taking on Iowa TV airwaves, from $3.1 million in ads from a super PAC supporting Romney as well as from Rep. Ron Paul's (R-Texas) campaign. Texas Gov. Rick Perry is also running an ad that hits Gingrich and Romney for their support of a health care mandate.

Gingrich launched an ad on Thursday to run in Iowa that responded in part to the attacks.

"These are challenging and important times for America. We want and deserve solutions. Others seem to be more focused on attacks rather than moving the country forward. That's up to them," Gingrich says in the ad, looking straight into the camera. "I believe bold ideas and new solutions will unleash America's creative spirit."

But he lags far behind the Romney campaign in organization and money -- a gap that has widened this week as Romney has hauled in over $4 million in fundraising. Perry, former Sen. Rick Santorum (R-Pa.) and Rep. Michele Bachmann (R-Minn.) are outworking Gingrich on the campaign trail. Santorum has been campaigning hard in Iowa for months, and Perry began a state-wide bus tour this week that will go through Jan. 3. Bachmann is launching a similar bus tour on Friday.

As Gingrich rose stratospherically earlier this month, it appeared he could gather such a head of steam that he could unite the conservative wing of the Republican party behind him and push aside the others, claiming the mantle of standard-bearer for those looking for an alternative to Romney. Over the last week or so, however, that scenario has begun to look less and less likely.

If Gingrich cannot claim a convincing victory in Iowa, that will make his path to the nomination much tougher against a Romney campaign that is very prepared for a long and drawn out primary, which is more likely than a quickly resolved contest.

Thursday night's debate -- the 13th of this primary -- will be another test. For Gingrich, he will need to reassert himself again. If he hopes to brush back the negative attacks on his record coming from Romney, this will be his most opportune moment to do so for maximum effectiveness. For Romney, it will be a test of how he responds to the inevitable charges from Gingrich that he is now running an all-out negative campaign.

Romney, who has not done many press interviews up until this point, conducted multiple interviews this week and has gone after Gingrich in increasingly personal terms. On Wednesday he called him "zany." Romney, whose personal net worth is estimated to be around $200 million, also said Gingrich is a "very wealthy man" because he ran up roughly $500,000 in debt at Tiffany's by buying jewelry for his wife, Callista.

Once the debate in Sioux City, Iowa, ends tonight, the candidates will have roughly a week to campaign in the state before voters begin tuning them out in the days leading up to Christmas. Once the electorate reengages, sometime a few days after Christmas, they'll have one more week for a final push.