Explained | The importance of Tuesday's 2024 New Hampshire primary

Contenders for the Republican presidential nomination will face off in the second contest of their nominating process on Tuesday in New Hampshire, while Democrats compete there on the same day in a battle expected to be significantly less competitive.

The Republican battle is down to two candidates—former President Donald Trump and former UN Ambassador Nikki Haley—after Florida Governor Ron DeSantis dropped out of the race on Sunday. The New Hampshire primary comes eight days after Iowa's Republican caucuses, which former President Donald Trump dominated. Haley will be eager to prove her bid is still viable despite Trump's nearly 30-percentage point victory in the Republicans' first nominating state.

Here are some key facts about the primary:

When is it? How does it work?

The New Hampshire primary will take place on Tuesday, with the precise hours dependent on the voting location. Unlike in Iowa and some other states, which rely on a relatively complicated "caucus" system, voters in New Hampshire cast their ballots much as they would during any other vote.

On the Republican side, 22 delegates to the Republican National Convention are up for grabs and will be awarded on a proportional basis. While that is a tiny portion of the 1,215 delegates needed to clinch the nomination, the state has traditionally played an outsized role in the nominating process because of its early spot on the calendar. For Democrats, 33 delegates will be sent to the Democratic National Convention from New Hampshire, but their vote won't be bound by the primary results after a dispute over the timing of the vote. That means the New Hampshire primary will serve purely as a barometer of support for the Democrats in the race. The national Democratic Party moved its first 2024 contest to South Carolina, which is significantly more diverse than New Hampshire's nearly 90 per cent white population, to better reflect the party. But New Hampshire state law requires it to host the first primary, and the Republican-controlled state government declined to make any legislative change to its primary date.

Who will be on the ballot?

The top Republican candidates on the ballot will be Trump and Haley. DeSantis and Haley placed second and third in Iowa, respectively. The main Democratic candidates on the ballot are US Representative Dean Phillips of Minnesota and self-help guru Marianne Williamson. Democratic President Joe Biden is running for reelection but will not be on the ballot because of the primary date dispute. Some of his supporters, however, have launched a write-in campaign on Biden's behalf.

Who is winning?

According to polling and analysis website 538, Trump leads the Republican field in New Hampshire with nearly 50 per cent of likely primary voters planning to cast a ballot for the former president. Haley is in second place with nearly 37 per cent support.

The Northeastern state is well-known for its relatively moderate, libertarian-minded brand of Republicanism. Moreover, the primary in New Hampshire is "semi-open," meaning voters who are not registered with any party can participate, which can help candidates perceived to be centrists, something that has made Haley competitive in the Granite State.

Biden is winning handily among Democrats, though the polling has been extremely inconsistent, with support for Phillips, his closest competitor, landing anywhere between the mid-single-digits and the upper 20s depending on the pollster. The fact that Biden supporters will need to write his name on the ballot adds another element of uncertainty.

What's at stake? Will it matter?

On the Republican side, most political analysts agree that New Hampshire presents Haley with her best opportunity to notch a victory - or at least a close second. She has gained significant momentum in the state in recent months.

If Haley fails to mount a spirited challenge to Trump, the former president could emerge as the presumptive Republican nominee to take on Biden in the November general election. If Haley does well, she will likely retain enough donors and interested voters to present a credible challenge in the subsequent weeks. Even if Trump loses, his competitors face an uphill battle. The former president leads Haley by roughly 36 percentage points in South Carolina, Haley's home state, where the next major nominating contest takes place in late February. Nationally, Trump holds a 37-point lead, according to the most recent Reuters/Ipsos poll.

New Hampshire represents an opportunity for Biden's Democratic challengers to prove there is appetite among voters to replace the party's incumbent. Biden has dedicated most of his energy to South Carolina, which is home of his party's first fully sanctioned contest and where support from the state's Democrats helped him secure the 2020 nomination.