In 2020, the general election polls missed Trump's support in key states, and the election came down to the wire. So far in 2024, though, polls don't seem to be understating Trump support. We'll see if that continues to hold.

—Dan Hopkins, 538 contributor

Something I’ve been turning over in my mind is whether Trump is more similar to an incumbent president seeking his party’s renomination, or to a candidate pursuing the nod in an open field. Trump has already been nominated twice by the GOP, and, obviously, occupied the White House for four years, making him perhaps one of the best-known people in the world. In that sense, he has a lot of the advantages of an incumbent. And it’s worth noting that some of the other presidents who have pursued non-consecutive terms, like Grover Cleveland and Theodore Roosevelt, also used the tools at their disposal — especially their ability to communicate with the public — to try to dominate their parties.

It matters for how we think about the eventual result. If Haley finishes with a strong second, that’s the kind of result that’s pointed to real vulnerability with past incumbents in New Hampshire. As Dan Hopkins pointed out earlier, competition in New Hampshire foreshadowed Lyndon B. Johnson’s decision not to run for reelection in 1968. George H.W. Bush was “jarred” in 1992 by Pat Buchanan taking 40 percent of the New Hampshire vote. And Gerald Ford had a narrow win over Ronald Reagan in 1976 in the vote totals, previewing not only a tough general election, but also brewing divisions in the GOP ranks.

This has implications for Biden as well, who is projected to win New Hampshire, despite not officially being on the ballot.

—Julia Azari, 538 contributor

DeSantis and Haley were vying to be the last opponent standing to Trump, and with DeSantis suspending his campaign over the weekend, Haley got her wish. An interesting side-effect is that we now have more of an ideological race. In a November 2023 survey, I found that Republicans evaluated Trump and DeSantis as similarly conservative. Haley, however, they saw as more moderate. So with DeSantis's departure, we have a clearer ideological divide.

—Dan Hopkins, 538 contributor

Trump tonight did something no Republican presidential candidate has done since President Ford in 1976: win both Iowa and New Hampshire in a contested primary. As I've been saying for a while, Trump is effectively the incumbent in this process — much in the same way that Ford was an incumbent with an asterisk in 1976. (He was the sitting president, but nobody had voted for him for anything.)

—Jacob Rubashkin, Inside Elections

At around 4:30 p.m., Americans for Prosperity Regional Director Greg Moore said on X (formerly Twitter) that he'd heard from sources in the New Hampshire secretary of state office that towns around the state had gone through more than 80 percent of GOP primary ballots available statewide, and that some towns were calling to ask for more to avoid running out. Polls in much of the state closed at 7 p.m Eastern, but a few places are open until 8 p.m.

Now, the Koch-affiliated AFP endorsed Haley to much fanfare earlier this cycle, so high turnout certainly would make Haley supporters feel hopeful about the number of independent voters taking part in the primary, who generally are more likely to support Haley than Trump. Still, ABC News's current total expected vote total in New Hampshire is 330,000 votes. Although that figure may change as the night wears on — it could go higher or lower — that many votes would represent nearly 30 percent of the state's entire voting-eligible population — that is, anyone who is eligible to register and vote. A turnout rate at that mark would be on par with the highest turnout in the state's modern history, which was the highly-competitive 2008 Democratic presidential primary.

—Geoffrey Skelley, 538