(CNN) -- Visiting New Hampshire, it appears that Mitt Romney is well poised to sweep through the Granite State, and probably South Carolina and Florida, on toward the nomination. But the campaign here suggests that, as he looks toward November, darkish clouds loom on the horizon.





New Hampshire voters love to surprise, and perhaps they will again this time. Some 37% remain undecided (according to a WMUR/UNH poll released Friday), and one can never be certain how many independents will vote nor whom they will support -- especially with Romney making several unforced errors in the past 48 hours.





Still, he has been a steady front-runner for months: His Massachusetts background makes him nearly a favorite son for many New Hampshire Republicans, and far more than in Iowa, his message of job creation resonates in this hard-hit state. He is almost cruising to victory.





So, the first question the press is asking is not whether he will win but by how much. If his vote total is in the mid-30s or better and he wins by double digits, the media will call it a major victory; if above 40, he will "crush." Only if he goes below 30, and that seems unlikely, will be he be seriously hurt.





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The related question is how others will stack up behind him. If there has been real news so far in New Hampshire, it is the lackluster performance of Rick Santorum. Typically, a candidate who came out of nowhere in Iowa to nearly win (what a difference those eight votes have made) would have built on that momentum in the first primary state. But Santorum appears to have plateaued and may even be fading.





That means the conservatives still don't have a darling to rally behind in South Carolina, leaving Romney once again to divide and conquer. Meanwhile, the Jon Huntsman team hopes that he can break through to second in New Hampshire or at least be in a tight cluster with Ron Paul. That would give him a chance to compete elsewhere, especially in Florida (where he first planned to have his headquarters).





But the fact that no one is yet challenging Romney for the brass ring this Tuesday means he is closing in rapidly on the nomination. Only one Republican (President Ford in 1976) has ever won back-to-back in Iowa and New Hampshire, and never before has a nonincumbent Republican done it. With a victory in South Carolina, Romney would be 3-0. With most of his rivals already forced to scrimp and save, who could raise enough money to take him on after that?





Even so, one cannot escape the sense in New Hampshire that if he is the nominee, Romney and his team still have serious work to do if they want to defeat President Obama. That was instantly apparent Sunday afternoon when Romney appeared with Gov. Chris Christie of New Jersey at a rally in Exeter, New Hampshire, drawing one of the biggest crowds of his campaign.





While supportive of their guy, the crowd seemed relatively quiet, almost subdued, a sharp contrast to the electric rallies that Hillary Clinton and Barack Obama held four years ago. Granted, the Democrats were locked in a much closer race. But several veterans of New Hampshire politics say that the energy isn't flowing as it has in years past.





That is consistent with a Pew poll announced Monday that found only 51% of Republicans and Republican-leaning voters nationwide rating this year's candidates as excellent or good, compared to 68% four years ago (and compared to 78% on the Democratic side in 2008).





Another striking (and related) impression on Sunday came with the speaking lineup. Normally, as a special guest, Christie would have taken the microphone first, warmed up the crowd, and then introduced the candidate, who would turn up the juice and send people marching into the night.





Instead, Romney spoke first, delivering a fairly boilerplate homily before handing off to Christie, who delivered a barn-burner (listening, one got
Who was the opening act for Christie in New Hampshire? Who has an edge in the gop Who needs to be the headliner Who else was in New Hampshire? Who has the edge in the GOP contest? Who is Barack Obama? Who is Romney running against?
Romney Romney Mitt Romney Chris Christie Mitt Romney President Rick Santorum.
question: Who was the opening act for Christie in New Hampshire?, answer: Romney | question: Who has an edge in the gop, answer: Romney | question: Who needs to be the headliner, answer: Mitt Romney | question: Who else was in New Hampshire?, answer: Chris Christie | question: Who has the edge in the GOP contest?, answer: Mitt Romney | question: Who is Barack Obama?, answer: President | question: Who is Romney running against?, answer: Rick Santorum.