If Donald Trump thinks he has the New Hampshire primary in the bag, he should think again.

A fascinating new survey of likely primary voters by the University of New Hampshire has found that Trump’s huge poll lead may be more vulnerable than we thought.

And that the man to watch for a strong second-place showing may be Florida Sen. Marco Rubio.

All eyes recently have been turned away from New Hampshire, whose primary takes place Feb. 9, to Iowa, whose presidential caucus will take place eight days earlier. It was in Iowa that Sarah Palin suddenly leapt into the fray by endorsing Trump, and where Trump is battling neck and neck with his chief Tea Party rival for the nomination, Texas Sen. Ted Cruz.

And it’s true that at first glance Trump appears to be running away with the vote in New Hampshire. If the primary were held tomorrow, likely voters in the state told pollsters that 34% of Republicans would vote for Trump, against just 14% for Ted Cruz, 10% apiece for Marco Rubio and Jeb Bush, and small amounts for various other candidates. (If there is a surge for New Jersey Gov. Chris Christie, as the GOP old guard fervently pray, it has not yet appeared.)

“ Among those who don’t tune in to talk radio, the picture is completely different: Trump has a net positive favorable rating of only 6%. ”

OK. But, as always with polls, you need to look at the fine print.

For example, the situation is still fluid. After all the publicity and all the debates, just 31% of likely voters say they have definitely decided on a candidate. A remarkable 43% still say they aren’t even leaning toward somebody — they’re undecided.

And although Trump so far has the most positive supporters, he also has by far the most enemies. An astonishing 30% of Republicans say they will definitely not vote for Trump “under any circumstances” — compared with just 4% for Cruz and Rubio.

And 40% of Republicans have a negative opinion of Trump, much higher than those for Rubio or Cruz. (Incidentally, Christie partisans should know he has very high negatives, of 47%.)

Furthermore, Cruz and Rubio get more than twice as many second preferences as Trump, something that may become significant if a few candidates emerge from the pack in the final days.

The UNH poll also shows the incredible role that talk radio plays in the Republican primaries. Angry, paranoid, right-wing radio is only the second genuinely American art form, after jazz, and it is alive and well today and driving the GOP base. According to the UNH poll, about 20% of likely GOP primary voters tune in regularly to angry voices like Rush Limbaugh, Sean Hannity and New England’s own fake populist, Howie Carr.

Sarah Palin endorses Donald Trump for president

And they have a totally different voting profile from those who don’t. (People who listen to Limbaugh are known as “dittoheads” and agree with whatever he tells them.)

Among talk-radio Republican voters, only three GOP candidates currently have net favorable ratings. Cruz is the clear favorite, with a net favorable 74%. Trump is second, with 44%. Rubio is third with 34%.

However, among the 80% who don’t tune in to talk radio, the picture is completely different.

Among them, Trump has a net positive favorable rating of only 6%. Cruz does better, but it’s only 12%, a fraction of his popularity among talk-radio fans.

Meanwhile, Rubio crushes it, with a net positive rating of 25%. He easily leads the field among Republicans who don’t listen regularly to talk radio. And he seems to be the only candidate who scores roughly equally with both groups.

Ladbrokes, the bookmaker, offers him at odds of 9/4 to be the Republican nominee and 6/1 to be the next president. Make of it what you will.