Primaries page. There are still very few polls being done in New Hampshire. Only two of them have been conducted since Trump's political media appearances began:
4/21 ARG -- Romney 32, Trump 17, Gingrich 8, Giuliani 8
4/03 PPP (D) -- Romney 27, Trump 21, Gingrich 12, Huckabee 12
2/14 WMUR/UNH -- Romney 40, Huckabee 7, Pawlenty 7, Palin 6
Individual polls mean little because the chance of inaccuracy is so high. But if they are all in agreement upon a certain point, it's likely to be true. Here, the conclusion to be drawn is that Romney will start the race in very good shape in New Hampshire.
Romney is at about the magic number of 30. In a race with several candidates, polling at 30% usually guarantees victory. The polls suggest that serious opposition to Romney is divided between Trump and Gingrich. For Romney to be threatened by either, one of the two will probably need to bow out of the entire race or flame out in spectacular fashion.
It was argued in a previous post that Trump is likely to have already reached something of a high-water mark: From now on, more and more voters will discover Trump's historic lack of commitment to the Republican party. By contrast, Romney's weaknesses (Romneycare, flip-flopping for the 2008 race) are already known to most primary voters.
As noted in the Candidate Rankings, New Hampshire is a do-or-die state for Gingrich, Romney, and Trump.
Barring a run by Christie, superb debate performances by Gingrich, a radical transformation of Trump, or truly inept handling of the Romneycare issue by Romney, it would seem at this point Romney has New Hampshire in the bag. The likelihood of one or more of those occurring--in particular a Christie run--is substantial. Even if Romney won New Hampshire, he would still need to face off against the winner(s) of Iowa and South Carolina. Elephant Watcher calculates Romney currently has a 10% chance of winning the nomination.