For many years, the New Hampshire primary was held in early March. As late as 1996 it was on 20 February. But as other states have been trying to get their cut of the early election attention, New Hampshire has had to keep moving earlier to stay ahead.

That means the primary now coincides with the low news season in much of the world, where people are still on holidays. So this week our TV screens, for want of other material, will be full of New Hampshire, just as last week they were full of its little brother, the Iowa caucuses.

Iowa shot to fame in 1976, when the little-known Jimmy Carter went on from victory there to win the Democrat nomination and ultimately the presidency. But its predictive record since then has not been particularly good; several Iowa winners have sunk without trace. By contrast, only two candidates have ever gone on to win the presidency after losing in New Hampshire.

Those two, however, are the most recent, George Bush Jr and Bill Clinton. And unlike all previous years, this year will see a huge nationwide primary just four weeks later, when almost half the states will vote on the same day. Hence a candidate like Rudy Giuliani, with (supposed) broad national appeal, feels able to ignore both Iowa and New Hampshire in the hope of scoring a knockout win on 5 February.

It’s a risky strategy, but it could yet work; as yet the Republican field is wide open, with no sign of support coalescing around any single anti-Giuliani candidate. New Hampshire might sort them out, but it might not.

The Democrat race is simpler, but probably more significant, since, whoever the nominee is, a Republican victory in November looks like a slim chance. For Hillary Clinton, New Hampshire is a must-win contest: even a narrow victory for Barack Obama, coming on top of his Iowa triumph, would give him huge momentum.

Obama on the other hand would survive a narrow loss in New Hampshire. To do his campaign serious damage, Clinton needs to win big – just as another front-runner, Ronald Reagan, did in 1980 after losing to Bush Sr in Iowa. It’s quite interesting to see how, even among the Democrats, everyone wants to be Reagan: this morning Andrew Sullivan is touting Obama’s claims to his mantle.

John Edwards, the only other serious prospect among the Democrats, depends on either Obama or Clinton being knocked out, leaving him as the only alternative to the survivor and therefore able to harvest their negatives. Despite positioning himself as the most left-wing candidate in the field, that means he could end up hoping that either racism or misogyny is still a powerful force.