Yes, Mitt Romney is going to win the New Hampshire primary tomorrow, unless something truly unexpected happens. Do the other results, including Romney’s margin of victory, matter? Yes — but mainly based on how Republican party actors and the news media interpret them.

So, what should we be watching for tomorrow?

1. Mitt Romney’s margin of victory. While I’d ignore any arbitrary numbers that the press or his opponents attempt to set in an effort to spin a Romney win as disappointingly small or even a loss, it’s also true that Romney has several advantages in the Granite State, and an unexpectedly narrow win would shake some of the certainty that’s developing about a Romney nomination. Brendan Nyhan was very good on this:

The “expectations game” is a key part of primary politics. It is in part a real phenomenon involving the reactions of key party actors to candidate performance. If a candidate underperforms relative to expectations, his or her standing with party elites, donors, and even voters may be diminished. The media should cover that process, just as it should cover candidates’ records and the substance beneath campaign rhetoric. However, journalists often exaggerate the effects of supposed over- or underperformance, in part by treating the conventional wisdom about how a candidate performed relative to expectations as some sort of objective fact rather than a social construction.

2. Can Rick Santorum keep his momentum going? A tricky one. Santorum seems (contrary to my expectations) to have stalled out in New Hampshire, and he’s currently struggling to beat Newt Gingrich for 4th place. Nationally, however, his Iowa bounce has been a healthy one, landing him in second place in Gallup’s national tracking poll. Will conservatives pay more attention to his (apparent) disappointing New Hampshire finish, or to his national and South Carolina numbers? The better he does in New Hampshire, the easier it will be for them to rally around him — if, that is, they want to, which is another key unknown at this point.

3. The third and perhaps biggest thing at this point to watch for: do the Republicans have a New Hampshire problem? If Mitt Romney, Jon Huntsman, and Ron Paul combine to take 80% or more of the vote, will conservatives seek to reform the nominating process by attempting to punish that state? The biggest complaint about Iowa and New Hampshire as the kick-off states in recent cycles has come from Democrats who object to the lack of ethnic diversity in those states, but a far greater problem could be that on the GOP side, moderates are overrepresented.

I suppose there are other things that matter around the margins. If Rick Perry really manages to finish behind Buddy Roemer, will that be enough to embarrass him out of the race? Is there any point Jon Huntsman can reach that might convince conservatives to consider him as a credible alternative to Romney? And if Newt Gingrich finishes fifth, will the press finally just ignore him? But I’ll stick with the three questions above as the big things to watch.