New Hampshire's primary rarely picks presidents but can still be influential

The New Hampshire presidential primary is Tuesday, and despite Donald Trump's commanding win in the Iowa caucuses -- and his persistent lead in polling around the country -- the race for the Republican nomination is not quite over yet.

In the last 20 years, not a single GOP winner in the Iowa caucuses went on to become president of the United States. But New Hampshire, which has long been the first primary in the country, offers one exception for conservatives in that same time: Trump himself.

His win in 2016, after narrowly losing in Iowa, was the first sign of how the party's voters were rallying to him on his way to the White House.

Trump is on track for a repeat victory on Tuesday, if the polls are accurate. Rival Nikki Haley has been closing the gap in recent weeks, somewhat, though she still trails by double digits, according to 538's average.

Here's a closer look at the history of the New Hampshire primary and its role in helping pick presidents.

How often does the New Hampshire primary winner become president?

Since 1920, New Hampshire has been the first primary in the country.

Together with Iowa -- whose caucuses kicked off both parties' nominating contests for five decades, starting in the '70s and ending this year -- New Hampshire has received outsized public attention because it offers the first glimpse at whom voters actually like.

But the state's preferences can be unique: In the last 104 years, there were only seven times that a presidential candidate who won a contested New Hampshire primary went on to the Oval Office.

That list includes Republican Dwight Eisenhower in 1952; Democrat John F. Kennedy in 1960; Republican Richard Nixon in 1968; Democrat Jimmy Carter in 1976, after the start of the modern primary system in which voters have a more direct role in selecting nominees; Republican Ronald Reagan in 1980; Republican George H.W. Bush in 1988 and Trump in 2016.

There were four times that the loser of a contested New Hampshire primary went on to become president: Republican George W. Bush in 2000 and Democrats Bill Clinton in 1992, Barack Obama in 2008 and Joe Biden in 2020.

Some of the more notable losses include Republican incumbent Harry Truman in 1952. "He took the attitude, 'I'm the president of the United States, I don't run in these silly primaries," said Saint Anselm College politics professor Christopher J. Galdieri.

Back then, before the modern primary system, presidential nominees were chosen via internal deliberations of the party. Voters had much less say.

Then-Tennessee Sen. Estes Kefauver won the 1952 primary over Truman, who soon bowed out of the race entirely. Galdieri said it was "the first time, and to date the only time, a sitting president actually lost a New Hampshire primary."

Galdieri said that some of the biggest defeats in New Hampshire's primary history were not when someone actually lost the race but rather had a "failure to meet expectations."

"Lyndon Johnson in 1968 technically won the [Democratic] primary. But Eugene McCarthy ... came so close that that was the big story coming out of the state," Galdieri explained.

He said that result was one of the many factors that pushed Johnson, then an incumbent president, to leave the race, setting up an eventual path for Hubert Humphrey to become the Democratic nominee. Humphrey ultimately lost in the general election to Richard Nixon.

The example of Johnson's underwhelming result is being cited in 2024 -- by Minnesota Rep. Dean Phillips, who is challenging Biden for the Democratic primary. While Phillips still lags Biden by a huge margin in the polls, per 538, he has cited how McCarthy helped end Johnson's campaign by exposing Johnson's electoral weakness.

Biden's allies, in response, are mounting a major write-in campaign for him in New Hampshire because he isn't technically on the ballot after a party dispute about the primary calendar.

The power of independents

New Hampshire's official motto "live free or die" goes back to the Civil War and the state has a famous independent streak. Today, nearly 40% of its voters are undeclared.

Undeclared voters can walk up on Tuesday's primary and vote for whichever party or candidate they like, and first-time voters can also show up and register on Election Day.

New Hampshire is famous for a midnight vote that takes place in a few very small communities. This year, the town of Dixville Notch, with six registered voters, voted right when the polls opened on Tuesday. All six chose Haley.

The amount of independents in New Hampshire affects which candidates succeed there. Notably, in this year's Republican race, Haley is doing much better in polls in New Hampshire than elsewhere and experts say it's because of her strength with non-Republican voters compared to Trump.

Like Iowa, many state residents pride themselves on being among the first people in the country to get an up-close-and-personal look at presidential candidates.

Author Scott Conroy, who wrote "Vote First or Die," said that "being the first primary gives it a special status that no other state can really touch."

"People do take the process very seriously in New Hampshire," he said.

Residents have often had years of meeting and greeting candidates and "ask questions that are atypical of the kinds of questions you get from reporters, so you have to be really quick on your feet," Conroy said.

However, the state's prominent position isn't without criticism: Neither Iowa nor New Hampshire is demographically representative of the U.S. as a whole -- both states are older, whiter and much less populated than other parts of the country.

'What matters is exceeding expectations'

New Hampshire only has 22 delegates, roughly half of Iowa, which has 40. Both of those numbers are a fraction of huge, diverse states like California, Florida, New York and Texas.

Republican candidates have to collect a total of at least 1,215 delegates to clinch the nomination.

"The number of delegates that you win coming out of New Hampshire is irrelevant," said Conroy. "What matters is exceeding expectations. Getting the media narrative and the wind in your sails ... people, generally, like winners in politics."

New Hampshire is known for its retail politics -- at diners, community meetings and town halls, fielding questions directly from the public -- which Galdieri said can be critical for candidates who are lesser known to nonetheless breakthrough on the national stage.

Galdieri points to Carter and McCain in years past. "Winning here or doing very, very well, better than people expect you to do, gives you a chance to introduce yourself to the country at large," he said.

"The quintessentially sort of mystical, New Hampshire mythology is that you don't have to have the most money, you don't have to have the most name recognition, because it's a small state, because it is sort of easily traversed over the course of a single day," Galdieri said.

ABC News' Amani Clemons, Kayla Panagrosso and Kelsey Walsh contributed to this report.