NRO's Jim Geraghty has piece up looking at the much-heralded independent vote today. Although independent voters make up a big portion of the New Hampshire electorate (anywhere from 30% to 40%, depending), there aren't as many up for grabs as you (or the media) might think.

Here's Geraghty:

There are roughly 375,000 undeclared voters right now in New Hampshire (out of a total of 850,000 registered voters). Maybe 40-45 percent of them will turn out to vote next Tuesday. (Roughly this percentage turned out in 2000, the last time we had contested primaries in both major political parties.) That's a universe of 160,000 voters. Of those folks, let's say 25 percent of them are truly independent voters. That's roughly 40,000 voters. If EVERY ONE of them were deciding between Obama and McCain (and I have seen absolutely no evidence for this, other than a few anecdotes), that would constitute a "swing vote" of 8 percent, assuming an overall turnout of half a million New Hampshire voters next Tuesday.

As Geraghty notes, the thing about independent voters is that they aren't all that independent. Whatever portion of the electorate is undeclared does not mean that it's up-for-grabs. Geraghty breaks down the numbers:

It is worth noting that in CNN's Jan. 4-5 poll, independents said they would split 51 percent for the Democratic primary, 49 percent for the Republican one, and two days earlier it was 56 percent for the Democrats, 44 percent for the Republicans. A week earlier it was 63-37 in favor of the Democrats, suggesting some volatility in those numbers, and the numbers were in that range for much of 2007.

Going with Scala's formula, if there are 160,000 undeclareds expected to vote tomorrow, then roughly 96,000 will vote in the Democratic primary and 64,000 will vote in the Republican primary.

If the split in CNN's most recent poll is accurate, 81,600 will vote in the primary for the Democrats, while 78,400 will vote in the primary for the Republicans.

Obama might be drawing some of those independents into the Democratic camp and some might be coming over based simply on their frustrations with Republicans. In any case, those Obama and McCain are fighting over constitute a small percentage.