Hanoi, Vietnam ? There are polls and there are polls. And in a Dartmouth College auditorium Tuesday night, the Republican presidential candidates indicated their selection for the front-runner in the struggle for the GOP nomination in a most unconventional, and most unmistakable, way.

Just after the halfway point of the two-hour session in a hall that ordinarily is the site for a cappella torch songs and Mahler symphonies, the eight candidates were invited to address a single question to one of their rivals. It was a chance to deliver a zinger — or maybe a knockout punch.

What happened was curious, and curiously revelatory. Four of them, including the two most pugnacious (Gov. Rick Perry of Texas and former House Speaker Newt Gingrich of Georgia), addressed their questions to former Gov. Mitt Romney of Massachusetts. The only other contender who was the object of more than one candidate question was pizza magnate Herman Cain, who received two.

Romney stakes his claim

That small episode was more than a swiftly passing wrinkle in the seventh Republican debate of the 2012 campaign. It clearly showed that Romney’s claim on the nomination is the strongest, and his responses — careful but convincing, flowing and fluent — served to emphasize his ascent.

Then came perhaps the most revealing moment. Romney had his chance to put one of his rivals on the spot. He chose Rep. Michele Bachmann of Minnesota, who as winner of the Iowa straw poll in August became a shooting star, but one who seems to be falling rapidly in the political sky, and his question wasn’t a shout or a shiv but instead a symbol of the emerging Romney way. With restraint and respect, he didn’t challenge Bachmann but instead invited her to set forth more of her economic views.

In a mere 10 seconds Romney did two things. He indicated that Perry and Cain weren’t significant enough threats to him to bother putting them on the defensive. And in a party that once preferred a scotch-and-soda cocktail hour to a tea party, he displayed a glimpse of the — dare this word be typed about the new GOP in the new century? — chivalry that marked the party of his father and most Republican fathers of yore.

Amid the rapidly changing leaves of New Hampshire’s tranquil Upper Valley this week, there was no mistaking the change in the tone, timbre and tensions of the Republican Party.

Hours before the Dartmouth do-si-do, Romney summoned the press corps to nearby Lebanon, N.H., but didn’t use the occasion to unveil yet another policy plank. After all, his plan has 59 points, more than Woodrow Wilson (14), God (10), Harry Truman (four) or Cain (with three, squared, comprising his mind-numbing 9-9-9 chant).

Instead, Romney had not a trope but a trophy — the endorsement of Gov. Chris Christie of New Jersey, lately the sweetheart of a swath of swooning Republicans who want to fall in love with anyone as long as he or she isn’t an already-announced candidate. This was the overture to the Mitt moment. The debate was the coda.

Now the Republican race has a new clarity, and a new tone. Romney sits atop the heap, in real numbers as well as in moments that stand as metaphors.

This week’s NBC News Poll taken by the Marist Institute, released hours before the debate, showed a slight Romney lead in Iowa but a decisive Romney advantage in New Hampshire, with his 44 percent more than three times bigger than his two closest rivals (Cain and Rep. Ron Paul of Texas, both at 13 percent) and seven times bigger than his putative (but increasingly less pugilistic) opponent, Perry, who in New Hampshire, if not nationally, is rapidly becoming an afterthought rather than a thoughtful alternative for a Republican morning after.

But the horse race numbers tell only part of the story. Here’s the rest:

Romney racks up big pluralities when poll respondents are asked which candidate is closest to them on the issues (38 percent), shares their values (35 percent) and can beat President Barack Obama (48 percent). Then there’s the question old-line Republicans used to ask: Who has the experience to do the job? This is a Romney landslide, with 63 percent.

GOP race has new feel

The change in the Republican race is palpable. The candidates once were hellions on a tear. Now they’re tired and tamed, no longer cocky, surprisingly cautious. The GOP race once seemed multilayered, like the granite outcroppings on a New Hampshire byway. Now there are only two, maybe three, striations left.

Romney has the momentum and the money, Perry only the money. Team Romney expects that the Texas governor, who played only a bit part in this week’s proceedings, will toss $1 million into New Hampshire, hoping that a polished media assault on Romney might do what an unpolished and unprepared debate performance has failed to do, which is to keep pace with Romney on the clubhouse turn of the run toward the nation’s first primary.

For a half-century, the Top of the Hop, an airy expanse perched on the campus arts center, has been a Dartmouth hub for after-class leisure, laughter and lies. Tuesday night it was filled with the saddest subspecies of homo politicus, the campaign spinners, and standing amid the carnival barkers was Rep. Debbie Wasserman Schultz of Florida, who heads the Democratic National Committee.

“It must be very frustrating to be a Republican tonight,” she said to no one in particular, and for a moment it seemed the product of yet another phase in the spin cycle. But later, in the cold air of a New Hampshire evening on a New England town green, and perhaps in the cool light of reason, the comment seemed illuminating for no other reason than that it may be an illusion.

Romney remains over-prepared and over-programmed. One, maybe two, of his rivals will have a moment in the sun, and my bet goes to Paul, who has worked the hardest and has yet to have his harvest. And it is a long way from a campus debate to a general election. But Tuesday showed that Romney’s Republican opponents — and Obama — have reason to be worried, maybe very worried.