New Hampshire is hosting the first presidential primary of 2024 on Tuesday — and the first big one-on-one contest between former President Donald Trump and a Republican rival.

Three GOP candidates have ended their campaigns since Trump’s blowout win in last week’s Iowa caucuses, including the man once pegged as his toughest competitor, Florida Gov. Ron DeSantis. DeSantis bowed out Sunday, immediately endorsed Trump and left behind former U.N. Ambassador Nikki Haley in the two-person race she had been coveting.

Unlike in Iowa, Democrats will vote Tuesday, too. But President Joe Biden, who engineered a primary season shakeup that prioritized South Carolina, won’t be listed as a choice on their ballots. Biden’s allies have mounted a write-in effort to spare him the embarrassment of losing a race that really offers only moral victories — or, potentially, moral defeats. 

Here are three storylines to watch:

What’s a win for Haley?

Haley’s expectations have fluctuated wildly since it became clear she had emerged as Trump’s chief rival in New Hampshire. DeSantis’ exit muddles things more. His poll numbers in New Hampshire didn’t make him a serious threat to Haley for second place, but many of his voters could flock to Trump and help him pad his lead.

After he endorsed Haley in December, Gov. Chris Sununu predicted she would win his state’s primary in a “landslide.” But Sununu has backpedaled, saying she could continue in the race with a strong second-place finish and set up a more consequential battle with Trump next month in South Carolina — a state where he leads in polls but where Haley used to be governor.

If Haley pulls off an upset Tuesday, she would head to her home state with a real semblance of momentum. If Trump prevails by a wide margin, pressure on Haley to drop out will intensify. If the result is close, Haley — like Sununu — might argue she has lived to fight another day. But the path to South Carolina and beyond doesn’t get much friendlier for her, because the base of the party isn’t exactly the base of Haley’s support. 

And even before South Carolina, there’s Nevada. Haley is on the ballot in the state’s official primary, but the Republican Party there is holding a caucus — and only the winner of the caucus will be awarded delegates. In other words, the next contest in early February won’t get Haley anything. 

Where does the old-guard GOP go from here?

Haley represents the traditional Republicans’ last stand — a reversion to the norm before the Trump storm eight years ago. Polls have shown her success is heavily dependent on moderates, independents and crossover Democrats who might be more inclined to vote for Biden in November if Trump is the GOP standard-bearer.

New Hampshire, where undeclared left-of-center voters are known for playing in GOP primaries, is the state most likely to deliver a sound rebuke to Trumpism. Sununu, who has rejected Trump’s style of politics but has suggested he would vote for him if he wins the nomination, is leading the charge for Haley there.

But Trump won New Hampshire’s primary easily in 2016, and the polls leading into Tuesday didn’t look promising for Haley. Given Trump’s appetite for vengeance and retribution, the Haleys and Sununus of the GOP might soon find themselves politically homeless.

“That’s the million-dollar question that I’m not sure I have the answer to,” former Maryland Gov. Larry Hogan, a centrist Republican who backs Haley and previously was a leader of the No Labels movement, told NBC News last week. “A lot of people are trying to figure that out.”

“If we don’t get it corrected this year, I think we are going to get back to that traditional Republican Party,” he added. “It just might take some time.”

Does Biden snatch a write-in victory?

The Democratic primary is a weird one.

Biden, who was embarrassed here four years ago to the point that he fled the state before the voting was finished and skipped ahead to South Carolina, attempted to end New Hampshire’s first-in-the-nation status. New Hampshire didn’t heed his wishes, so the show will go on — without him.

Rep. Dean Phillips, D-Minn., and self-help author Marianne Williamson are on the ballot and, unlike Biden, campaigned in New Hampshire. Then there’s the progressive effort to encourage Democratic voters to write in “cease-fire” as a protest of Biden’s Israel policy.

Although the results won’t count toward delegate allocation, there’s a chance that everyone loses: Biden if the write-in operation backing him proves less than robust, Phillips if he proves to be more gadfly than Eugene McCarthy, Williamson if she remains the footnote she was in 2020.