Trump's big Iowa win included some signs of trouble with moderates, younger voters

Monday was a big night for former President Donald Trump: He won a clear victory in the Iowa Republican caucuses -- the first chance voters had in the 2024 race to register how much (or how little) they supported him over rivals like Ron DeSantis and Nikki Haley.

But beyond the headline of Trump's 51% win, there were more insights in the results.

Here's a closer look at what happened in Iowa and what's next for Trump.

Strong showing overshadows some issues

An analysis of entrance polls of the caucusgoers on Monday showed the various Republican groups with whom Trump excels -- as well as the areas in the electorate where he is relatively weaker.

He won big with caucusgoers ages 45 and older (56% support), those without a college degree (67%) and Republicans (54%), conservative voters (55%) and "very" conservative voters (51%) as well as 53% of white evangelical Christians, according to the entrance poll analysis, produced by Langer Research Associates for ABC News.

Trump was also overwhelmingly favored (82%) by those caucusgoers looking for a candidate who "fights for people like me" and saw robust support as well (64%) from those caucusgoers who said they were focused on immigration, the entrance poll analysis found.

What's more, 46% of voters identified themselves as part of the "MAGA movement" that Trump started and most (78%) of that group supported him.

Broad swathes of the electorate on Monday embraced two of his key views: 63% of caucusgoers said they'd consider him fit for office even if he were hypothetically convicted of a crime, according to the analysis. Trump faces charges in four cases but has pleaded not guilty.

And two-thirds (66%) of the caucusgoers said they further believed the false claim that President Joe Biden wasn't legitimately elected over Trump in 2020.

Added together, these findings from the entrance poll indicate an Iowa Republican base that is older, conservative, less college educated, more religious and partial to MAGA views -- all of which go along with their support for Trump.

The entrance poll results show some issues he still faces with other voters -- moderates, younger people, four-year college graduates -- suggesting he could have a problem in courting those same kinds of groups beyond the GOP base.

According to the entrance poll analysis, Trump won just 37% of four-year college graduates, 42% of independents and 20% of moderates.

He also earned a minority of caucusgoers who wanted a candidate with "the right temperament" and lost out to DeSantis on voters focused on abortion and to Haley on voters focused on foreign policy.

Turnout dropped a lot

The Iowa caucuses are a quirky part of the presidential nominating process every four years.

Because they are held first out of every state, they receive outsized media and public attention as the first example of how voters actually feel about the candidates.

But the caucuses' rules are not like a traditional election, instead requiring that participants gather at the same time across the state and participate in forum-like meetings before casting their ballots.

Perhaps as a result, turnout has been lower than in contests in other early voting states, like New Hampshire.

This year saw turnout drop sharply from the last contested caucuses, in 2016. About 110,000 people participated in the caucuses -- a roughly 40% decline from eight years ago, which set a record high for turnout. (By contrast, New Hampshire's 2016 primary saw more than 250,000 votes cast.)

Punishing winter weather was ultimately a factor for caucusgoers to deal with, Iowa Republicans said, after projecting that voters were used to such conditions and would not be swayed.

"Iowans braved record-low temperatures after a blizzard blanketed their state just days earlier to deliberate with members of their community about the future of our country and participate in true, grassroots democracy," the Iowa GOP chair, Jeff Kaufmann, said in a statement.

"Iowans coming out en masse demonstrates our people's resilience and determination, as well as their confidence in the most transparent democratic process in the country," Kaufmann said.

Trump's 51% total was by far the widest margin of victory in any meaningfully contested Iowa Republican caucuses dating to their start in 1976.

But allies of some of his challengers were quick to insist that the relatively low turnout means the results shouldn't be overinterpreted and nearly half of all caucusgoers still chose someone other than Trump.

Trump's path from here

The results of the caucuses were the first proof from Republican voters that Trump remains dominant with the party's base -- but his path to a third straight presidential nomination is not without obstacles.

He'll next compete in New Hampshire's primary on Tuesday, where Haley is a much closer No. 2 to him in polling, compared to other states.

Like Iowa, New Hampshire has some unique rules of its own that could favor Haley, polling indicates.

The primary is open, meaning both registered Republicans and independents can vote. Haley has been winning notable support from independents.

She is making a major push to persuade those voters to turn out for her on Tuesday and give her key momentum before South Carolina's primary at the end of February. (Nevada will hold its Republican caucuses in early February but Trump has trounced in all of the state polling there that is tracked by 538.)

However, the path to competing with Trump long-term is a narrow one, if the polls are accurate. He is still the clear favorite -- by double digits -- in various states and nationwide. And Haley and DeSantis are still tangling with each other, each pushing to be the main Trump alternative.

Away from the trail, the former president must also contend with his legal troubles. While he denies all wrongdoing, his ability to campaign is and will continue to be complicated by various court proceedings related to his criminal cases.

In February, the U.S. Supreme Court will also hear arguments about a challenge to his candidacy under the 14th Amendment's "insurrection clause," with his opponents arguing that his alleged involvement in Jan. 6 should bar him from holding future office.

He has dismissed that, calling it anti-democratic.

ABC News' Christine Filer, Gary Langer, Isabella Murray, Oren Oppenheim, Steven Sparks and Kelsey Walsh contributed to this report.