For Newt Gingrich, the batch of recent polls showing him with a double-digit lead in Iowa is a mixed blessing. Especially in a caucus, people like to show they are with a winner, so the bandwagon effect is real. However, Gingrich’s numbers on caucus night, according to local Republicans, may be soft, given his relative lack of organization. Without a fleet of supporters to get friends and neighbors to the caucuses, the actual results may not mirror his lofty poll numbers.

If he wins by a smaller-than-expected margin, his opponents are likely to claim a “moral” victory. At the Republican Jewish Coalition presidential forum in Washington on Wednesday, Gingrich was already talking about eight years in the White House, picking out his secretary of state and predicting that his own coattail effect would help GOP members of Congress. If he fails to impress on caucus night all of that will be thrown back in his face, and we will certainly hear more criticisms that he is a victim, once again, of his own massive ego.

Craig Robinson of the Iowan Republican tells me he met with a group of undecided caucus-goers on Wednesday. “We spent most of the time discussing Gingrich. There were people who are leaning his way but don’t want to commit because they are fearful of what may come out between now and the caucuses. They are refusing to fully commit because they want to reserve the right to change their minds — I think a byproduct of the Herman Cain saga and the result of a tumultuous caucus cycle.”

It is also the case that as Gingrich becomes a more established front-runner, he becomes less appealing to many serious conservatives who are worried about electability. The Wall Street Journal editorial board at one time was ready to chase Mitt Romney out of the primary, but now it praises his entitlement reform plan as infinitely preferable to Gingrich’s noisy speechifying:

Personal Social Security accounts are desirable, but that doesn’t mean it makes sense to reject compromises that reduce future liabilities. Yet Mr. Gingrich proposes no such changes in his plan, perhaps because they are politically unpopular. But such an abdication opens him up to charges that he’s not serious about reform and that he has no plan to pay for the transition costs of going to personal accounts . . .Given his Social Security dreams, Mr. Gingrich’s timidity on health care is especially puzzling. . . .

After denouncing Paul Ryan’s premium support Medicare reform as “right-wing social engineering” in May, Mr. Gingrich now says he supports it as long as it is only voluntary. As with Social Security, people could continue to receive today’s unreformed, open-ended benefits if they preferred. This model may be politically safer and perhaps more saleable to voters, but it also does little to improve the status quo. Why would anyone leave the all-you-can-eat buffet without an incentive to choose cost-conscious options?

Mitt Romney also says he’ll leave fee-for-service Medicare untouched, but the key difference is that under his plan all seniors would receive the same defined contribution. They’d pay the marginal cost above this fixed subsidy, increasing competition for the health-care dollar among insurers and hospitals, doctors and other providers.

So we shouldn’t overlook the possibility of an upset win in Iowa by a Gingrich rival. The most likely candidate for that may be Rep. Ron Paul (R-Tex.). The key to his success, especially in straw polls (which is essentially what the caucuses are), has always been his intensely loyal fans. Paul is back in Iowa today, and reports suggest his troops are enthused. Moreover, he’s been one of the candidates most willing to attack Gingrich, in Web and TV ads and in interviews. He told ABC News, “He’s been on a lot of different sides on all the issues. He may be the opposite of what I’ve been doing for 30 years. My positions haven’t changed all that much.”

Paul’s ability to shower the electorate with his anti-Gingrich message, the intensity of his supporters and the opportunity to make two more pitches to his base of support in debates on Dec. 10 and 15 may help him give Gingrich a scare. At the Ames straw poll (which seems a lifetime ago), Rep. Michele Bachmann (R-Minn.) was the prohibitive favorite. Nevertheless, Paul lost by only 152 votes, a margin of less than 1 percent of the vote. Should he likewise narrow the margin with Gingrich at the caucuses he will certainly claim that he’s stopped the Newt-mentum. Can he win Iowa? Robinson says: “Absolutely, especially if Newt has a misstep or sees his support wane. Paul’s campaign is well organized, focused and motivated.”

Then there is Texas Gov. Rick Perry, who’s throwing everything he’s got into ads and making a hard sell for Christian conservatives. At the RJC event, he reminisced, “I feel a special connection to Israel, dating back nearly 20 years when I first visited the Holy Land. I have been to the Western Wall, that most sacred of symbols where Jewish pilgrims gather to pray today and that has withstood the assaults on the Jewish people since the times of the early Romans. I walked in the footsteps of the heroes of Massada, a fortress of defiance symbolizing their loyalty to freedom more than life itself.” Heavy on the the schmaltz, but also a solid pitch to evangelical pro-Zionist Christians.

Even less subtle is his pitch on the social issues. In his most recent ad, Perry tells voters: “I’m not ashamed to admit that I’m a Christian, but you don’t need to be in the pew every Sunday to know there’s something wrong in this country when gays can serve openly in the military but our kids can’t openly celebrate Christmas or pray in school.As president, I’ll end Obama’s war on religion. And I’ll fight against liberal attacks on our religious heritage. Faith made America strong. It can make her strong again.”

In short, while Paul attempts to pry hardcore fiscal conservatives away from Gingrich, Perry is hoping for a share of the religious right voters. Perry’s still in single digits in most polls, but if he can drain off votes from Gingrich, Paul may the beneficiary.

Then there is Mitt Romney, whose insistence on not making Iowa a priority looks wise now. He’s essentially deadlocked with Paul in recent polls. There’s no doubt he’d like to finish at least second, but a Paul victory would puncture the Gingrich bubble and allow him to regain his footing. He’s bringing New Jersey Gov. Chris Christie into the state, showing off his wife ( Read: his only wife, unlike Gingrich) and doing much more media. If he can partially close the gap with Gingrich he hopes to recapture some momentum, setting himself up for a long primary battle that his camp thinks will favor him.

Bachmann and Rick Santorum will have two more debates and the benefit of having spent time on the ground in the state. Santorum’s crowds have been growing. They are hoping that the polls just haven’t yet registered the uptick in excitement. If one of them can finish ahead of the other and also in front of Perry, that may provide a boost and rationale for continuing on to New Hampshire. Otherwise, it’s likely the end of the trail.