Democratic presidential candidates Pete Buttigieg and Bernie Sanders were neck and neck Thursday in the chaotic Iowa caucuses with 100 percent of precincts reporting but no winner declared following technical issues.

The tally comes hours after the Democratic party chairman ordered a review of the results following technology problems that prevented a complete vote count in the United States' first nominating contest Monday and some doubts were raised about the accuracy of the process.

Sanders, the leftist senator from Vermont, and Buttigieg, the former mayor of South Bend, Indiana, are separated by a razor-thin margin in the final results, which come three days after the caucuses.

Democratic presidential candidate Joe Biden speaks to a supporter in Somersworth, New Hampshire
Democratic presidential candidate Joe Biden speaks to a supporter in Somersworth, New Hampshire GETTY IMAGES / SPENCER PLATT

Democratic Party chairman Tom Perez, however, stepped in earlier Thursday, demanding a review of the caucuses.

"Enough is enough," Perez said on Twitter. "In order to assure public confidence in the results, I am calling on the Iowa Democratic Party to immediately begin a recanvass."

Perez said it would involve an examination of the results from each caucus site rather than a full recount.

Yard signs for Democratic presidential candidates in front of a home in Manchester, New Hampshire
Yard signs for Democratic presidential candidates in front of a home in Manchester, New Hampshire GETTY IMAGES / JUSTIN SULLIVAN

With returns in from all of the 1,765 precincts in Iowa, Buttigieg was leading by 26.2 percent to Sanders's 26.1 percent in the delegate totals.

Massachusetts progressive Senator Elizabeth Warren was next with 18.0 percent followed by former vice president Joe Biden with 15.8 percent and Minnesota Senator Amy Klobuchar with 12.3 percent.

Democratic presidential hopeful Pete Buttigieg, pictured at a town hall meeting in Concord, New Hampshire, appears to be getting a bounce from his strong performance in Iowa
Democratic presidential hopeful Pete Buttigieg, pictured at a town hall meeting in Concord, New Hampshire, appears to be getting a bounce from his strong performance in Iowa AFP / Joseph Prezioso

Earlier in the day, Buttigieg declared himself the winner based on the number of delegates from the Midwestern state who will be sent to the Democratic convention in July while Sanders claimed victory based on the popular vote.

"It has been an extraordinary week, and we are absolutely electrified... by the extraordinary validation of this campaign's vision that we had in Iowa," Buttigieg told military veterans and other voters Thursday at American Legion Post 98 in Merrimack, New Hampshire.

He also turned an eye toward the state's primary vote, to be held Tuesday.

Democratic presidential candidate Bernie Sanders speaking at a campaign event in Derry, New Hampshire
Democratic presidential candidate Bernie Sanders speaking at a campaign event in Derry, New Hampshire GETTY IMAGES / JOE RAEDLE

"So I know in the days leading up to primary day it is my responsibility to seek to earn every vote in a state that famously thinks for itself, in a state that lives by the motto of 'Live Free or Die.'"

Sanders, speaking Thursday in nearby Manchester, pointed to his lead in Iowa's actual vote totals.

"In other words, some 6,000 more Iowans came out on caucus night to support our candidacy than the candidacy of anyone else," he said.

"From where I come from, the person who gets the most votes wins," Sanders said, arguing that too much emphasis was being put on delegate totals.

Democratic presidential candidate Elizabeth Warren holds a baby during a campaign stop in Exeter, New Hampshire
Democratic presidential candidate Elizabeth Warren holds a baby during a campaign stop in Exeter, New Hampshire GETTY IMAGES / JOE RAEDLE

At the end of the day, he said, the caucus system is "much, much, much too complicated" and it was a mistake for the state party to "rely on untested technology."

Party officials have blamed the technical meltdown on a "coding error."

President Donald Trump pounced on the debacle in the first-in-the-nation contest to decide which Democrat faces him in November.

"The Democrats, they can't count some simple votes, and yet they want to take over your health care system," Trump said in remarks celebrating his acquittal at his Senate impeachment trial.

Buttigieg appeared to be getting a bounce from his strong Iowa performance as the latest New Hampshire poll showed the centrist candidate in second place in the Granite State.

The Boston Globe/WBZ-TV/Suffolk University poll had Sanders, who won the New Hampshire primary four years ago before eventually losing the nomination to Hillary Clinton, topping the field with 25 percent.

Buttigieg's support surged to 19 percent from 12 percent on Monday, according to the poll, while Biden saw his backing slide over the same period.

Biden, the national frontrunner who described his likely fourth-place finish in Iowa as a "gut punch," met with advisors on Thursday to map out strategy.

"I expected to do better," Biden, 77, said as he launched attacks on rivals.

"If Senator Sanders is the nominee for the party, every Democrat in America... will have to carry the label Senator Sanders has chosen for himself," Biden said of the self-described democratic socialist.

Biden, who served in the Senate for 36 years before becoming Barack Obama's vice president, said 38-year-old Buttigieg's lack of experience was "a risk" for Democrats.

The Sanders campaign announced, meanwhile, that it had raised $25 million in January, its largest fundraising month yet.

Pat Clark, a 70-year-old New Hampshire salesman listening to Buttigieg in Merrimack, said he is opposed to Sanders.

"I'm a moderate, so I'm not into giving away the whole store," Clark told AFP, referring to Sanders' plans for universal health care and tuition-free college.

After New Hampshire, the candidates turn their sights on Nevada on February 22, South Carolina on February 29 and then the March 3 "Super Tuesday," when 14 states hold primaries.