What to know about the upcoming New Hampshire primary

With Iowa's caucuses in the rearview mirror, New Hampshire's primary is up next.

With 22 GOP delegates at stake, campaigns are making their way through New Hampshire before the Jan. 23 primary -- with their sights set on the state's undecided voters.

As the first-in-the-nation presidential primary election approaches, here is what to know.

What does New Hampshire mean for presidential candidates?

New Hampshire will be a major test for former U.N. Ambassador Nikki Haley and Florida Gov. Ron DeSantis after they finished far behind former President Donald Trump in the Iowa caucuses. As with Iowa, Trump is the front-runner in New Hampshire, according to 538's recent polling averages in the state.

Undeclared voters -- also known as independent voters -- will be a main focus in the New Hampshire primary. With more undeclared voters than those registered as Republican or Democrats, their votes will be valuable in the state's open primary. In 2024, more than 100 of those undeclared voters will opt to cast ballots in the competitive Republican contest.

Of the remaining GOP presidential hopefuls, Haley has spent the most time in New Hampshire with 49 events spread over 35 days in the state. Behind her is DeSantis who has done 40 events over 18 days in New Hampshire. Trump has done the fewest events with 12 events spread over 10 days in the state.

President Joe Biden will not be on the ballot in New Hampshire. According to the Democratic National Committee rules, he is prohibited from competing. After months of refusing to come into compliance with DNC calendar guidelines, Biden's campaign wrote in a letter to New Hampshire Democrats in October informing them that the president would not be filing in their primary.

Democrat challengers, such as Dean Phillips and Marianne Williamson, have campaigned in New Hampshire; however, they won't be granted delegates as the Democratic party will not recognize its results.

What to know about the primary

New Hampshire state law mandates that polls be open for a minimum of eight hours. Polls must close no later than 8 p.m.

There is at least one location that holds voting at midnight -- making it the first place to open voting on primary day: the infamous Dixville Notch.

New Hampshire is an open primary: registered Republicans and independents can vote in the Republican primary; registered Democrats and independents can vote in the Democratic primary; independents can participate in either the Republican or Democratic primaries.

Voters had until the evening of Oct. 6 to change their party registration. They are not allowed to change it on the day of the primary.

The biggest portion of changes this cycle were Democrats to undeclared -- with more then 3,500 voters making the switch, according to data released by New Hampshire Secretary of State David Scanlan.

There are 25 Republicans and 21 Democrats on the ballot. It only takes paying $1,000 and filing out a form to get on the ballot.

Some people on the Republican ballot include former candidates such as North Dakota Gov. Doug Burgum, former New Jersey Gov. Chris Christie, former Vice President Mike Pence, tech entrepreneur Vivek Ramaswamy and South Carolina Sen. Tim Scott.

The state's famously inclusive rules allow college students from other states to vote, as long as they don't vote anywhere else. And every four years, voter fraud watchdogs are on the lookout for votes from New Hampshire's many vacation property owners, along with the many political volunteers who spend long stretches in the state.

'First-in-the-nation' pride

New Hampshire takes pride in being first. In February 2023, the DNC approved a new presidential primary calendar that stripped New Hampshire of its "first-in-the nation" status. Iowa now happens before New Hampshire -- however, since Iowa uses caucuses, New Hampshire still maintains the distinction as the first primary on the calendar.

"New Hampshire has held the first-in-the-nation presidential primary election for over 100 years," Scanlan said when announcing the primary date back in November.

"In today's society, it seems that we're quick to eliminate traditions and ignore them. But years from now the people of this country will really be glad we still have this one."

New Hampshire also has pride in its high voter turnout -- ranking third in the nation for participation -- 72% of eligible voters participated in the 2020 presidential general election.