Pete Buttigieg is narrowly leading the Democratic presidential field in the Iowa Caucuses, according to initial returns that the party at last began reporting late Tuesday afternoon following a massive delay linked to technical breakdowns.

But Vermont Sen. Bernie Sanders is close behind the former South Bend, Ind., mayor, with 71 percent of precincts reporting in the first batches released by the embattled state party. Sanders is also ahead in the popular vote, with 24 percent to Buttigieg's 21 percent, Elizabeth Warren's 19 percent and Joe Biden's 15 percent.

It was still not clear when the party would release the complete vote totals.

The returns relevant to delegate count show Buttigieg with 26.9 percent and Sanders with 25.2 percent. Warren trailed with 18.4 percent and Biden was hovering in fourth with 15.4 percent, just ahead of Minnesota Sen. Amy Klobuchar.

Those numbers were not reflective of the initial popular vote in Iowa. In the caucus system, supporters of "non-viable" candidates who perform poorly in the first round of caucusing are free to throw their support behind other candidates in future rounds. Then, those final vote totals determine how many delegates each candidate receives from Iowa at the Democratic National Convention.

CLICK TO SEE THE IOWA RESULTS

A Buttigieg campaign source told Fox News that the preliminary and incomplete results confirmed that Buttigieg performed well in key rural counties. On Monday night, even before any official results were released, Buttigieg claimed he had emerged "victorious" from the caucuses.

Senior Sanders adviser Jeff Weaver, meanwhile, told Fox News the campaign was "gratified that in the partial data released so far, it’s clear that in the first and second round, more people voted for Bernie than any other candidate in the field.”

Klobuchar campaign manager Justin Buoen wrote on Twitter that the results "make clear" the presidential contest "is a five person race." He added that some of Klobuchar's "strongest counties haven't been fully reported and the current data doesn't tell the full story."

Because of the closeness of the race, and the limited data released by the Iowa Democratic Party, Fox News' Decision Desk has not yet made a final call concerning the winner in the Iowa caucuses.

Nevertheless, taking the stage at a campaign event Tuesday afternoon in Laconia, New Hampshire, Buttigieg once again declared virtual victory, citing the new vote count.

"A little later than we anticipated, but better late than never, official verified caucus results are coming in from the state of Iowa," Buttigieg began. "They're not complete, but results are in from a majority of precincts, and they show our campaign in first place."

He added: "No matter what happens next, this much is undeniable: that fact represents an astonishing victory for this campaign, this candidacy and this vision that you all have been a part of."

While incomplete, the results could mark a disappointing finish for Biden considering his past status as the unrivaled front-runner. Biden drew small crowds at precincts in Iowa on Monday.

"I don’t see how Biden recovers," an ex-2020 presidential campaigner staffer told Fox News. "His whole argument is electability. If he can’t do well in a state like Iowa, how can he do well on Super Tuesday?"

If the numbers hold, both Buttigieg and Sanders may be able to claim momentum, albeit belatedly, heading into the next crucial presidential primary contest in New Hampshire.

The announcement of the partial vote totals came as Iowa Democratic Party Chairman Troy Price offered a public mea culpa for the overnight fiasco while defending the accuracy of the data in hand.

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“I apologize deeply for this,” he said at a press conference, calling Monday night’s chaos “simply unacceptable” and pledging a thorough and independent review.

He said party officials “hit a stumbling block” on the back end of reporting the data but insisted “this data is accurate.”

He faulted a “coding error” but said the party has a paper trail to back up the results.

While Buttigieg and Sanders were already touting initial results even before Iowa's party reported them, a victory by any candidate likely will be clouded by the confusion and general campaign frustration over the meltdown in Iowa over the past 24 hours.

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Several top campaigns and their supporters blasted the process and the state party, with the overheated recriminations essentially depriving the eventual victor of the sort of clean, prime-time win that would ideally accompany the first-in-the-nation contest result.

From here, the field hit the trail in New Hampshire ahead of next week’s primary election, where party leaders are already boasting of a much simpler and cleaner process.

New Hampshire “uses paper ballots and has run smoothly for 100 years. We expect a great turnout in the Democratic Primary by Democrats, Independents and those who register on Primary Day. It is a magical week in the Granite State,” New Hampshire Democratic Party Chairman Ray Buckley told Fox News.

The Iowa Democratic Party, meanwhile, has scrambled to explain what went wrong and fend off critics eager to challenge the state’s status at the front of the presidential nomination calendar. On Tuesday morning, the party blamed a “coding issue” in its reporting app but stressed that the debacle “did not impact the ability of precinct chairs to report data accurately” and claimed the issue was fixed.

“We have every indication that our systems were secure and there was not a cybersecurity intrusion. In preparation for the caucuses, our systems were tested by independent cybersecurity consultants,” Price said in a statement.

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Price said the party’s initial investigation determined “with certainty” that the data collected through the app was sound but that “it was reporting out only partial data. We have determined that this was due to a coding issue in the reporting system. This issue was identified and fixed. The application’s reporting issue did not impact the ability of precinct chairs to report data accurately.”

The chairman said that because of mandated paper backups, “we have been able to verify that the data recorded in the app and used to calculate State Delegate Equivalents is valid and accurate.”

Fox News' Michael Tobin and Ellison Barber contributed to this report.