Do the Iowa caucuses predict the president? What history says

Iowa's first-in-the-nation caucuses are fast approaching, with Republican candidates duking it out in the final days before the first major test of their electability.

However, history shows that winning in Iowa does not guarantee success in the rest of the primary race -- or in November.

Since 1972, Iowa's caucuses -- this year set for Monday -- have been a testing ground for presidential candidates and an opportunity for White House hopefuls to inject a surge of momentum for their campaigns in other states.

Still, in the five decades since the start of the modern primary system, there were 16 times that presidential candidates that won the Iowa's caucuses have not gone on to become the commander in chief (not including uncontested races).

There were eight times that the Iowa caucuses' winners were not named their party's nominee (again, not including uncontested races).

Only three presidents since 1972 won their Iowa caucuses when the races were contested rather than unopposed: Democrats Jimmy Carter in 1976 and Barack Obama in 2008 as well as Republican George W. Bush in 2000.

There are a few Iowa losers who went on to win: Ronald Reagan in 1980, George H.W. Bush in 1988 and Donald Trump in 2016.

Some of the more notable instances in the past decade include Republican candidate Mike Huckabee's 2008 Iowa caucuses win.

That year, Huckabee won the caucuses with 34% -- far ahead of the eventual GOP nominee, Sen. John McCain, who came in fourth with 13%.

In the 2012 Iowa caucuses, Republican Rick Santorum barely beat out eventual nominee Mitt Romney -- with Santorum winning by just 34 votes.

Four years later, Ted Cruz won the Iowa caucuses, besting Trump by about 3%. But Trump, of course, went on to become the party's nominee and then be elected president later that year.

On the Democrat's side, in 1992, Tom Harkin trounced the eventual party nominee and president, Bill Clinton -- 76% to 3%, respectively.

And more recently, Pete Buttigieg very narrowly won the Iowa caucuses with 26%. The party's eventual nominee and winner in the general election -- Joe Biden -- came in fourth with 16%.

Expert: 'Politically, Iowa should not matter'

One of the main reasons Iowa's track record for picking future presidents is inconsistent is that the state, while the first to weigh in on the presidential race, does not reflect the rest of the nation, said Sean Westwood, a Dartmouth College associate professor of government and director of the university's Polarization Research Lab.

What appeals to Iowa voters may not resonate with the rest of the county's voters, Westwood told ABC News.

"I think the general point is that politically, Iowa should not matter. It's homogeneous, it's rural and it's overwhelmingly white. And those who win in Iowa often don't become president, because Iowa caucuses just don't reflect the policy preferences and demographic composition of America," Westwood said.

It's one thing to win in Iowa, Westwood said, but completely different to win in a battleground state such as Arizona, Georgia or Pennsylvania, which have more diverse electorates, both racially and socioeconomically.

Iowa's caucuses historically involve representatives for each candidate pitching that candidate in hopes of winning over their fellow caucusgoers. These public, communal, discussion-heavy meetings require a big organizational effort from campaigns -- from volunteers to getting voters to show up to voice their support, said Dr. Todd Belt, a George Washington University professor and director of its Political Management program.

Because of this, Iowa has required a different strategy to win -- one that some candidates have excelled in, Belt said.

"We don't get a sense from polling of who's actually going to turn out and do the physical work of going. It's easy to say you're gonna go. It's another thing to actually go and do it," Belt said.

That has allowed for some "dark horse" winners over the years, Belt noted -- such as Santorum.

"And the reason for that is because getting people to caucuses is much more difficult and an entirely different enterprise than getting somebody to check the box for you in an election," he said.

'The reason Iowa is important'

Iowa's 40 delegates mean "very little" in the grand scheme of things, Belt said. For context, there are more than 2,000 unpledged delegates available to win in this year's Republican primary race.

However, because Iowa is the first contest, it helps narrow the presidential field and allows voters their first real up-close-and-personal chance to meet candidates, according to experts. The results also have outsized influence on media coverage and public perception.

"The primary process is a long process and the first couple of states -- Iowa, New Hampshire -- are small states. It actually gives some lesser-known candidates an ability to get out there and talk with voters and gives them a chance that they might not have if we did it all at once, and you had just some high-dollar candidates with great name exposure running," Belt said.

Winning in Iowa also helps candidates build a foundation that can help them beyond the caucuses, Belt said.

"The reason Iowa is important is because there are three critical resources that allow you to extend your campaign beyond New Hampshire, and those are volunteers, campaign funds and endorsements. And if you don't place first, second or third in Iowa, all those are going to dry up for you. And you're probably not going to be able to make it through the long and arduous journey of the rest of the nomination campaign," he said.

Winning in Iowa may not offer much voter support in the long term, but it can help candidates raise the money needed to wage a successful campaign, Westwood said.

"You have a chance to build a war chest that can be helpful in future states," he said.

A 'testing ground for campaigns'

Win or lose, the momentum from doing well in Iowa can help candidates compete in the next contest, New Hampshire's primaries -- set for Jan. 23 this year. The two states have similar demographics and go hand-in-hand, said Belt, who added that he sees New Hampshire as a "test of electability" while Iowa is a "test of organizational strength."

"If you do well in both of those [states], then that is a signal to potential contributors, volunteers and endorsers that you can really make a mark and go further down the field, and that you are worthy of the media attention that comes with that as well," Belt said.

Candidates have a chance to succeed beyond the early states if they can find what resonated with those voters and apply that nationally, Westwood said.

"I would see primaries and caucuses as a testing ground for campaigns. It's a place where there's a lot of access to voters, and where there's a lot of interest from voters," he said.

"But I think it's key for campaigns to not see it as a fait accompli for the presidency, but to see it as an opportunity to have really close connections with voters and to really identify what matters and what's effective and in the 2024 landscape."

This cycle, Trump has the enduring lead over other GOP candidates -- with about 51%, according to 538's latest Iowa polling averages.

Still, anything can happen with more than 300 days until Election Day, Belt said, and if Trump loses the Iowa caucuses -- while an unlikely scenario -- the other candidates could find an opportunity.

"If Donald Trump loses, could he still win? Absolutely. There's plenty of time after Iowa, to regroup and to extend your campaign," Belt said.

"It's much more important for those other candidates in the race to show that they do have the organization and the strength to be able to be a potential rival to Donald Trump, or even be more electable than him if they went one-on-one against Joe Biden," he said, "which is what they're going to try to say."