According to a January poll from the St. Anselm College Survey Center, Republican primary voters said they were less likely to vote for Trump in November than they are to vote for Haley. Twenty-one percent of GOP primary voters in New Hampshire said they would vote for Biden in a race between Trump and Biden. If the matchup were between Haley and Biden, just 10 percent said they would choose Biden.

—Mary Radcliffe, 538

Like most incumbent presidents, Biden appears to have avoided a serious threat to his renomination. His main opponents, Dean Phillips and Marianne Williamson, are extremely unlikely to win the party's nod. However, unlike his recent predecessors (and his major 2024 opponents), Biden didn't file for the New Hampshire ballot because the state's primary date violates the Democratic National Committee's calendar rules for the 2024 cycle, which upset New Hampshire Democrats by threatening their state's long-held spot as the first-in-the-nation primary. Yet many Granite State Democrats are also working to help Biden win as a write-in candidate to avoid allowing one of his fledgling opponents to claim victory. And polls have found Biden comfortably leading the field despite his write-in status, although his support has ranged from about 50 percent to 70 percent.

This isn't an unprecedented situation: In the 1960s, President Lyndon Johnson twice won as a write-in candidate. While New Hampshire's primary has included a presidential preference vote since 1952, the 1964 Democratic ballot didn't have any candidate names in the preference section — Johnson won 95 percent as a write-in. But in 1968, his less-convincing write-in performance had a much bigger impact and likely played a role in his exit from the race. Amid frustration over Johnson's handling of the Vietnam War, Minnesota Sen. Eugene McCarthy challenged him in New Hampshire and, unlike Johnson, put his name on the primary ballot. Johnson fell just short of 50 percent and only won by about 8 points over McCarthy. In the days following the primary, New York Sen. Robert Kennedy jumped into the race, and Johnson soon surprised the country by announcing that he wouldn't seek renomination.

Phillips, who usually polls better than Williamson in New Hampshire, is a long-shot to actually defeat Biden, but McCarthy's 1968 showing looms large as an example of how a sizable vote share in defeat can still count for much. Other past examples of strong incumbent challengers also stand out. In March 1952, Tennessee Sen. Estes Kefauver did the unthinkable by actually defeating President Harry Truman outright in the Democratic primary, 55 percent to 44 percent, which led Truman to announce he wouldn't seek renomination. In February 1976, President Gerald Ford only outdistanced former California Gov. Ronald Reagan by little more than 1 point in New Hampshire and went on to barely edge out Reagan for the GOP nomination. In 1980 and 1992, incumbent presidents Jimmy Carter and George H.W. Bush won their party primaries by 10 and 16 points, respectively, showcasing intraparty divisions that may have contributed to their reelection defeats in November.

—Geoffrey Skelley, 538

Last week I wrote a bit about Iowa's poor track record when it comes to selecting GOP nominees for president; it's been 24 years since the winner of the Iowa caucus went on to secure the Republican nod. So it's only fair we give New Hampshire the same treatment.

While you have to go back to 2000 to find an instance of Iowa voting for the eventual nominee, you have to go back exactly that far to find a time when New Hampshire didn't vote for the ultimate winner. That was the year John McCain rode his "Straight Talk Express" to a 49 to 30 percent upset over George W. Bush. Since then, the winners of every contested Republican primary (McCain again in 2008, Mitt Romney in 2012 and Trump in 2016) have become the nominee.

Looking back even farther, New Hampshire's record is similarly impressive. From 1952 through 1996, the state held 10 competitive GOP primaries, and in all but two of them the winner went on to claim the party's nomination. In 1964, U.S. Ambassador to South Vietnam Henry Cabot Lodge Jr. defeated Arizona Sen. Barry Goldwater 36 to 22 percent. Despite not campaigning or formally declaring as a candidate (he was in Saigon the whole time), Lodge garnered write-in protest votes from liberals upset with Goldwater and was boosted by an endorsement from former President Dwight D. Eisenhower. And in 1996, New Hampshire opted narrowly for Pat Buchanan over Sen. Bob Dole by just 2,136 votes, making it one of just four states Buchanan ultimately carried.

—Jacob Rubashkin, Inside Elections

A couple weeks ago, Leah Askarinam wrote an interesting article about which voters were fueling Haley's recent rise in the polls. It turns out, the answer was largely college-educated voters. Nationally, about 20 percent of college-educated Republicans were telling pollsters they backed Haley, but only about 5 percent of non-college-educated Republicans supported the former U.N. ambassador.

While nationally, college-educated Republicans still preferred Trump, in New Hampshire, Haley was actually leading Trump among that demographic:

That's good for Haley, considering that New Hampshire is one of the most college-educated states in the nation: 41 percent of Granite Staters age 25 and over have a bachelor's degree. And the electorate today is probably going to be even more educated than that. According to exit polls, 53 percent of voters in the 2016 Republican primary in New Hampshire were college graduates.

—Nathaniel Rakich, 538

It's been only eight days since Iowa's first-in-the-nation caucuses last Monday, but a lot has happened since then. On the night of the caucuses, businessman Vivek Ramaswamy dropped out of the race and endorsed former President Donald Trump, and Florida Gov. Ron DeSantis followed suit on Sunday. With former Arkansas Gov. Asa Hutchinson also leaving the race last week, former U.N. Ambassador Nikki Haley is Trump's last major competitor standing.

And everyone has their eyes on New Hampshire as potentially the only state where Trump has a realistic chance of losing. Haley has invested heavily in New Hampshire and has been suggesting since early December that today's race would be the start of a competitive two-person primary between her and Trump. She's got her two-person race, but whether it will be remotely competitive remains to be seen. Trump has only continued to consolidate party support since his Iowa victory, and anything less than a convincing win for him would be surprising.

So when might we know? First polls will close tonight at 7 p.m. Eastern, and last polls will close at 8 p.m., which is the earliest time we could have a race projection. But as we did last week (when Trump's victory was projected only 30 minutes after caucuses had begun), we will of course be sticking around no matter what happens to see how each candidate does across the state and discuss what it could mean for the rest of 2024.

And that's not all! Granite State Democrats also have a primary today, and it's a weird one — New Hampshire is violating Democratic primary calendar rules by holding it so early. As a result, President Joe Biden isn't campaigning or even on the ballot, but his competitors, Rep. Dean Phillips and self-help author Marianne Williamson, are. While Biden isn't expected to face serious competition for the actual nomination, his margin of victory today as a write-in candidate could be one early sign of Democrats' grassroots enthusiasm for the incumbent.

Bookmark this page for updates and analysis throughout the night!

—Tia Yang, 538