Huckabee: The major question now looming over his surge -- is it for real? -- will be emphatically answered by how he finishes in the caucuses. If Huck can withstand the pounding he's taking (and will continue to take) from Romney and Romney allies as well as the heightened scrutiny he's getting from the MSM, he'll be a serious contender into New Hampshire and beyond. If he can't succeed in a low-turnout caucus dominated by his kind of people (His kind of people, if you will) he's Howard Dean.
He may have hit a poll plateau, but his crowds here this week have been very good and there remains a loud buzz about his candidacy in the grassroots. He's bringing in some more staff firepower and is finally starting to drop mail. He'll never have what Romney has on these measures -- organization and voter contact -- but he draws the sort of passion Mitt lacks. And he has key allies in local radio, home-schoolers, FairTaxers and evangelicals that Mitt lacks (aside from his own quiet Mormon support)
Romney: A loss in Iowa would be devastating to his campaign. He can embrace the underdog role all he wants, but given the time he's spent, resources he's invested and organization he's constructed, he's the closest thing to the establishment candidate here. And when the establishment candidate doesn't win a GOP primary/caucus, it's a big, big story.
Mitt's folks are increasingly optimistic about Iowa. They see Huck falling back down to earth in polling and are counting on the mainstream conservative vote to win the day. The better the weather and higher the turnout the stronger their chances. They recognize that if they can chop Huck's lead down to within the margin of error, their organization can deliver enough points to pull out the w.
I disagree slightly with J-Mart on Romney--I think he survives a close-ish second, particularly if Rudy and McCain finish pretty far out of the money. (If, on the other hand, one of them finishes a strong third in Iowa, that's a big problem for him.) But with McCain surging in New Hampshire, he can't finish too far behind Huckabee in Iowa--that's clearly true.
Update: Boy, did I lead with my chin on that one. Not only is McCain surging, but a Boston Globe poll out today shows him nearly tied with Romney in New Hampshire--25 to Romney's 28. If that's an accurate reflection of what's going on, Romney really does have to win Iowa to have a clear path to the nomination. That's not to say he can't win if he doesn't. There are worse positions to be in a week into the primaries than to be sitting on two second-place victories and a $300 million fortune, particularly at a time when your rivals face a tough fundraising environment. But, if he loses Iowa, the GOP race will be wide open.