What then? The next contest is New Hampshire on Jan. 10, where Mitt Romney continues to hold a solid lead and where Jon Huntsman has been building support that could push him above Paul and Gingrich for second place.
Ten days later comes South Carolina, which was decisive in determining the Republican nominations in 1988, 1992, 1996, 2000 and 2008. Gingrich's big leads there, scored when he was leading nationally, may already have vanished or surely will if he lags in the first two contests.
Each hypothetical contender in South Carolina has some weakness. Romney has seen Perry, Herman Cain and Gingrich far outpoll him -- a sign of real voter resistance. Paul's poll numbers are lower than in Iowa and New Hampshire, and in this high-turnout primary it will be harder for his small number of activists to make the kind of impact they can in low-turnout Iowa.
As for Santorum and Huntsman, neither starts off with any appreciable support or organization in South Carolina. Neither has the Southern background or military record that helped the George Bushes and John McCain win here.
As for Florida, which votes Jan. 31, the Romney campaign has been working it quietly for months. They'll have plenty of money for TV in a state twice as populous as the other three put together, a head start where they won in 2008 (Jacksonville and the Gulf Coast) and important Cuban-American endorsements in Miami.
None of this guarantees a victory for Romney, but most of it points in that direction. Back in November, Gingrich predicted that Romney would crack under pressure and would fall by the wayside. It looks like the opposite's been happening.