New Hampshire voters are headed to the polls on Tuesday. After Donald Trump’s landslide victory in the Iowa caucus last week, his two top rivals for the Republican nomination – the Florida governor Ron DeSantis and the former UN ambassador Nikki Haley – hope to make a splash in the critical primary state.

But the Republican primary is not the only contest being held in New Hampshire on Tuesday. New Hampshire Democrats are moving forward with their own primary, one with a major asterisk: Joe Biden’s name will not appear on the ballot as the Democratic National Committee has said that the New Hampshire primary is “meaningless” after party officials moved to make South Carolina the first voting state.

Here is everything you need to know about the New Hampshire primary:

How is the New Hampshire primary different from the Iowa caucuses?

New Hampshire will hold the first primary election of the 2024 election cycle, while Iowa held the first caucuses of the Republican nominating contest. In a caucus, each voter is required to appear in person at a specific precinct location to cast a ballot, as the Guardian’s Martin Pengelly explained earlier this month.

A primary is much more straightforward, with polling locations across the state open for a set number of hours to allow voters to cast their ballots. Because of the relative ease of voting and the option for undeclared voters to participate in either party’s primary, New Hampshire generally sees higher turnout than Iowa.

In 2020, roughly 176,000 Iowans participated in the Democratic caucuses, while nearly 300,000 New Hampshire voters participated in the Democratic primary. The turnout gap is particularly notable considering Iowa’s population is more than twice the size of New Hampshire’s.

Which Republican candidates are on the ballot?

Two dozen candidates filed the necessary paperwork to appear on the Republican primary ballot in New Hampshire, but the overwhelming majority of votes are expected to be cast for DeSantis, Haley and Trump.

After their disappointing performances in Iowa, entrepreneur Vivek Ramaswamy and former Arkansas governor Asa Hutchinson both dropped out of the Republican primary. Their names will still appear on the ballot, as will the names of other former candidates like the former vice-president Mike Pence and the South Carolina senator Tim Scott.

Related: Who’s running for president in 2024? The Republican and Democratic candidates

Are New Hampshire Democrats also holding a primary?

Yes, but it’s complicated. The Democratic National Committee voted last year to designate South Carolina as the party’s first primary state moving forward, while New Hampshire would have the opportunity to vote second.

The decision outraged New Hampshire Democrats, who insist they will not go along with the national party’s plan to rob them of their “first-in-the-nation” status. As a result, the New Hampshire Democratic party decided to hold its primary the same day as the Republican primary in defiance of the DNC’s decision.

The DNC has criticized the New Hampshire primary as a sham, calling on the state party to “educate the public” that the contest “is a non-binding presidential preference event and is meaningless”. The New Hampshire attorney general, Republican John Formella, in turn sent a cease-and-desist letter to the DNC to compel the organization to stop making “false, deceptive and misleading” claims about the primary.

Because of the standoff, Biden’s name will not appear on the New Hampshire primary ballot, although many Democrats still plan to vote for him as a write-in candidate. Other long-shot candidates, including Minnesota congresswoman Dean Phillips and self-help author Marianne Williamson, will appear on the ballot and hope to capitalize on New Hampshire Democrats’ frustration with the change in the voting calendar.

Related: US elections 2024: a calendar of the key events

Who can vote in each primary?

Voters who are registered as a Democrat or a Republican may only vote in their party’s primary, but undeclared voters may choose to participate in either primary. There are already indications that Democrats and independents in New Hampshire plan to participate in the more competitive Republican primary, as thousands of voters changed their registration leading up to the deadline in October.

The presence of independent and Democratic voters in the Republican primary could dramatically affect the results. Haley in particular hopes that she can sway enough of those voters to chip away at Trump’s advantage with more hard-right Republicans.

Which Republican candidate is expected to win New Hampshire?

Polls show that Trump remains well ahead of DeSantis and Haley in New Hampshire, although Haley has significantly narrowed the former president’s lead in recent weeks. According to the FiveThirtyEight average of New Hampshire polls, Trump is about 13 points ahead of Haley, but he was leading by 25 points last month.

What might New Hampshire tell us about the Republican primary moving forward?

Haley hopes that a strong showing in New Hampshire will bring a definitive end to DeSantis’ campaign, even though the Florida governor finished ahead of her in the Iowa caucuses. A Suffolk University/NBC10 Boston/Boston Globe survey conducted after the Iowa caucuses showed DeSantis polling at just 6% in New Hampshire.

Haley has tried to make the argument that the primary is now “a two-person race” between her and Trump because of DeSantis’ low polling numbers in New Hampshire and South Carolina, which will hold its Republican primary late next month. Haley is betting that, if DeSantis drops out of the race, she can consolidate the support of non-Trump voters and overtake the former president. But as the results of the Iowa caucuses showed, there may not be enough non-Trump voters left in the Republican party for Haley to pull off an upset.

How do the demographics of New Hampshire compare with the rest of the country?

New Hampshire is generally whiter, older and wealthier than the rest of the nation. According to the American Community Survey conducted by the US Census Bureau, 90.5% of New Hampshire’s voting-age residents identify as only white, compared with 67.1% of all American adults who identify as such. Only 1.1% of New Hampshire residents over 18 identify as Black and 3.1% identify as Hispanic, while 12.3% of all American adults identify as Black and 14% identify as Hispanic.

New Hampshire also has a higher share of citizens over the age of 65, with 25% of its adult residents in that age bracket compared with 23.2% of all American adults. The median age of all New Hampshire residents is 43.3, which is older than the 39.0 median age for all Americans.

In terms of household wealth, 7.2% of New Hampshire adults report an income that falls below the poverty level, compared with 11.1% of all Americans whose incomes fall below that level. And while 94.1% of New Hampshire’s adult residents have at least a high school degree, 91.3% of all Americans over 18 can say the same.

Because of the demographics of New Hampshire, a number of critics have challenged the state’s early voting status. In its move to push the New Hampshire primary to a later date, the Democratic National Committee cited the racial diversity of other early states like South Carolina and Nevada to justify their prioritization in the voting calendar.

“This calendar looks like the Democratic Party, and it reflects the diversity of America,” the DNC chair, Jaime Harrison, said last year.

When do polls close in New Hampshire?

Polls will close at 7pm ET, and results will start coming in shortly after that. The Guardian has several reporters on the ground in New Hampshire on Tuesday, and our live blog will share results and analysis as polls close, so stay tuned.