DES MOINES — Former South Bend, Ind., mayor Pete Buttigieg emerged Tuesday as the early leader in the Iowa caucuses, running ahead of Sen. Bernie Sanders (I-Vt.) and other top Democrats, according to partial results released Tuesday after almost a day of delay and confusion.

While Buttigieg quickly declared himself the victor and tried to build momentum for his candidacy, the release of preliminary results from the beleaguered caucuses did little to contain the chaos that rocked the first-in-the-nation nominating contest or to settle a jumbled field of Democrats vying to prove they are the best candidate to defeat President Trump.

“A campaign that started a year ago with four staff members, no name recognition, no money, just a big idea — a campaign that some said should have no business even making this attempt, has taken its place at the front of this race,” Buttigieg said in New Hampshire after the preliminary results were released. “And no matter what happens next, this much is undeniable: That fact represents an astonishing victory for this campaign.”

According to the early results, which Iowa Democratic Party Chairman Troy Price said represented 62 percent of the state’s precincts, Buttigieg was leading with 26.9 percent of the state’s delegates, followed by Sanders with 25.1 percent. Sanders won some bragging rights with a popular-vote lead, with 28,220 to Buttigieg’s 27,090.

Sen. Elizabeth Warren (D-Mass.) and former vice president Joe Biden were in third and fourth place with 18.3 and 15.6 percent of the delegates, respectively — disappointing results for candidates who have sought to push the idea that they are most electable. They ranked in the same positions in the popular vote.

The full results remained delayed Tuesday after a complex caucus process plagued by technical difficulties in its reporting system that began Monday night and continued with no clear timeline for a resolution. The Iowa Democratic Party said Tuesday that it was continuing to try to verify the results, collecting boxes of presidential preference cards and pushing precincts to report their results as quickly as possible.

“We’re going to take the time that we need to get these results done,” Price told reporters Tuesday.

Despite the uncertainty, Buttigieg’s early showing could propel the historic candidacy of a young Midwestern former mayor who has pitched himself as the candidate best equipped to win back Rust Belt voters lost to Trump in 2016. Buttigieg, a 38-year-old military veteran vying to become the country’s first openly gay president, had been clear about the importance of a strong Iowa showing to the viability of his upstart campaign.

Buttigieg’s voice seemed to crack Tuesday as he acknowledged the unprecedented nature of his success. “It validates for a kid somewhere in a community wondering if he belongs or she belongs or they belong in their community, if you believe in your country, there’s a lot backing up that belief,” he said.

His challenge will be to build on the result in an overwhelmingly white state by improving his lackluster poll numbers with minority voters in coming contests.

For his part, Sanders’s result sent a message to the Democratic Party about the hunger for an economic populist and the desire to upend the party’s establishment.

Highlighted by Biden’s underperformance, Tuesday’s results began to reshape the already restless Democratic primary contest, drawing former New York mayor Mike Bloomberg to invest more heavily in his un­or­tho­dox campaign and putting pressure on the other candidates to quickly establish themselves as viable alternatives.

As they descended on second-voting New Hampshire early Tuesday, before the Iowa results were released, the contenders sought to strike an upbeat tone, releasing favorable internal figures and claiming moral victories.

“I’m someone that thrives in chaos,” Sen. Amy Klobuchar (D-Minn.) told supporters in Concord. “You want a steady hand in chaos, right?”

Klobuchar was in fifth place in Iowa, according to the partial results, with 12.6 percent of the state’s delegates. Entrepreneur Andrew Yang trailed behind with 1.1 percent, and businessman Tom Steyer had 0.3 percent.

The results, while partial, flashed warning signs for the party and several of its top-tier candidates, who appeared to underperform on key metrics. While Sanders came out on top in the popular vote, the overall turnout figures — comparable to 2016’s but far below the record numbers that launched Barack Obama’s candidacy in 2008 — indicated that his pledge to energize an army of young and first-time voters had not been fulfilled.

Warren’s distant third-place position solidified her retreat from the top of the polls over the summer. It was an underwhelming result for a candidate who had invested heavily in organizing support in Iowa and hoped that would boost her in the end.

The results were especially bad for Biden, a former vice president and six-term senator who found himself trailing two liberals and a moderate while struggling to prove his viability in a party that appeared to be moving on from him.

Lingering concerns about Biden’s sluggish campaign style, small crowds, mental missteps and middling fundraising could intensify as he seeks to temper expectations about a potential second loss in New Hampshire.

Biden’s campaign appeared to lose votes as the multi-round caucus process progressed, an ominous sign for his electability argument. Yet after staking his candidacy on his appeal to black voters, who cast ballots later, he expressed optimism before the results were released.

“We don’t know precisely how many votes we had, but I feel really good about getting more than my fair share,” Biden said Tuesday during a campaign event in Nashua, N.H.

The muddled results served to persuade lower-tier candidates to stay in the race, making the Democrats’ challenge to select a standard-bearer all the more difficult. Some candidates, like Klobuchar, appeared to be emboldened, pledging to continue their campaigns to compete in New Hampshire’s primary Tuesday.

The results also bolstered one candidate who was not competing in Iowa: Bloomberg.

As the caucus competitors waited for results Tuesday morning, Bloomberg authorized his advisers to double television spending for his campaign. The increase represents a massive escalation of what was already the most costly campaign for the Democratic nomination in U.S. history.

As his advisers described the Iowa result as the best-case scenario for the billionaire candidate, Bloomberg said he was prepared to continue spending more of his fortune on his bid.

“Someone said, ‘Are you spending too much money?’ and I said, ‘I’m spending money to get rid of Donald Trump,’ ” Bloomberg said Tuesday in California, one of the Super Tuesday states where he has focused his efforts. “And the guy said, ‘Spend more.’ ”

Trump campaign officials, who had massed in Iowa ahead of the caucuses, were all too willing to capi­tal­ize on the Democrats’ troubles with tallying votes. Trump’s allies said the results showed that Democrats were ill-equipped to govern the country. Republicans also interjected conspiracy theories into the mix, suggesting without proof that the delays were part of a scheme to rig the race against Sanders, who was leading in the polls.

Some of Sanders’s allies also appeared to raise questions about whether their candidate had been the victim of a conspiracy, though the self-described Democratic socialist did not traffic in those rumors.

Sanders said Tuesday that he felt he was in “pretty good shape” based on his campaign’s tally of caucus results, but he stopped short of declaring victory and suggested that Buttigieg had prematurely portrayed himself as the winner. “I don’t know how anybody declares victory before you have an official statement as to the election results,” Sanders said.

Warren’s allies had hoped for a second-place finish in Iowa and have tried to frame the results as a three-way cluster at the top with Biden lagging behind. That description is intended to deflate his candidacy and offer her the chance to consolidate some of his support.

Warren’s backers said the results provided no real springboard for any of the top three candidates.

“Nobody is going to get a momentum story out of this. That has been decided. It is just not happening,” said Adam Jentleson, a Warren ally and onetime top aide to former senator Harry M. Reid (D-Nev.).

Still, several candidates who had flown overnight to New Hampshire sought to convince voters and the media that they had left the Hawkeye State with momentum.

Biden began his Tuesday event in Nashua by opining on the still-undecided caucuses, claiming that his campaign was “really doing well” in the state. But hours earlier, Biden’s team blasted the Iowa Democratic Party for its handling of the vote and pushed to block the premature release of the results.

“We believe that the campaigns deserve full explanations and relevant information regarding the methods of quality control you are employing, and an opportunity to respond, before any official results are released,” his campaign said in a statement to the party.

Sanders’s advisers released several batches of incomplete and unofficial numbers that they said were the results of an updated internal tally, based on information collected by precinct captains. The count, which the campaign said was based on 60 percent of precincts, showed Sanders leading on the first and second votes, but did not specify delegate totals or precinct-level information.

After the results were released, Sanders’s campaign touted the raw vote total that showed him in the lead.

Addressing reporters after the results were made public, Buttigieg called the numbers “the best piece of news our campaign has gotten since we entered this race” and predicted that it would “propel us into a great position to compete.”

Warren addressed the debacle in Iowa at the top of her first public event in New Hampshire, a town hall at a theater in Keene.

“We had a bumpy start to the democratic process yesterday in Iowa,” she said before the numbers were released.

During the event, she sought to frame the results as essentially a three-way tie, casting her campaign as one that’s going to be in the hunt for quite a while.

“We’ve done Iowa,” she said to the crowd. “We’ve got New Hampshire in just a week! Are we ready to do New Hampshire?”

Paul Schwartzman, Michael Kranish, Matt Viser, Cleve Wootson Jr. and Sean Sullivan contributed to this report.