Pete Buttigieg ended his presidential campaign on Sunday, in an abrupt and surprising pullout that further narrows the field of Democrats less than a month after he declared victory in the contested Iowa caucuses.

"I will do everything in my power to ensure that we have a new Democratic president come January," Buttigieg told a throng of enthusiastic and emotional supporters in South Bend, Ind., on Sunday night, in a speech marked by an upbeat and forward-looking timbre.

"We sent a message to every kid out there wondering if whatever marks them out as different means they are destined to be less than," he continued amid chants of "USA!" and other cheers. "To see someone who once felt that exact same way can become a leading presidential candidate with his husband at his side."

Buttigieg's husband Chasten introduced the candidate by remarking through tears that "Pete got me to believe in myself again. ... I told Pete to run because I knew there were other kids that needed to believe in themselves, too."

Buttigieg had been scheduled to headline a rally in Dallas on Sunday night. The charter plane was rerouted.

Buttigieg's withdrawal comes just days before 14 states are set to head to the polls on Super Tuesday, where one-third of all delegates for the nomination will be at stake. His exit likely will harm frontrunner Bernie Sanders by providing a coalescing boost to more moderate candidates, as Buttigieg had gone on the offensive against the Vermont senator and sought to appeal to the centrist base of the party. Many early votes have already been cast, however.

A senior campaign aide told Fox News the decision was "absolutely not" because of Buttigieg's failure to reach his Super Tuesday fundraising goal of $13 million. The campaign announced Sunday that it needed another $1.6 million to reach that target.

"Pete believes this is the right thing to do for our country, for our party and for Americans across the country eager to heal our divided nation, defeat this president and work to fix our broken politics," the aide said.

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Hours earlier, speaking to NBC News' "Meet the Press," Buttigieg vowed that "we'll be assessing at every turn not only what the right answer is for the campaign, but making sure that every step we take is in the best interest of the party and that goal of making sure we defeat Donald Trump -- because our country can't take four more years of this."

Last week, Buttigieg told Fox News' Peter Doocy that "by Super Tuesday, we could be on an irreversible trajectory toward nominating Senator Sanders unless we come together around an alternative; I'm offering to be that alternative."

Buttigieg narrowly defeated Sanders by delegate count in Iowa, but has since suffered a string of defeats culminating in his drubbing in South Carolina on Saturday, where he finished fourth, behind billionaire Tom Steyer.

President Trump, meanwhile, repeatedly derided what he called Buttigieg's resemblance to the pathetic cartoon character Alfred E. Neuman from Mad magazine. Buttigieg also faced criticism for allegedly plagiarizing former President Barack Obama's speeches and imitating his intonation.

"Pete Buttigieg is OUT," Trump wrote on Twitter Sunday. "All of his SuperTuesday votes will go to Sleepy Joe Biden. Great timing. This is the REAL beginning of the Dems taking Bernie out of play - NO NOMINATION, AGAIN!"

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The former South Bend, Ind., mayor has had limited political experience, but sought to build his campaign on his military service and the possibility that he could become the first openly gay president.

Buttigieg struggled winning over black voters in particular. During a visit to Allendale County in South Carolina last December, he remarked, "I know that as somebody who’s new on the scene, I’ve got to earn that trust and we’ve got to have those conversations."

He received only nine votes on Saturday in the county, compared to Joe Biden's 552, Tom Steyer's 241, Sanders' 119 and Elizabeth Warren's 17.

Analysts generally have agreed now that the nomination is increasingly likely to come down to a race between Biden, who won by a large margin in South Carolina, and Sanders, who secured the popular vote in Iowa, Nevada, and New Hampshire.

In a memo on Sunday, though, Warren's campaign said there would likely be a contested convention -- and promised to make a "final play" for the nomination there. Buttigieg outperformed Warren in each of the early primaries and caucuses.

"After Wisconsin, nearly one-third of the pledged delegates will still be waiting to be elected, and there will be a three-week gap between electing delegates for the first time since voting began," Warren campaign chief Roger Lau wrote. "In the road to the nomination, the Wisconsin primary is halftime, and the convention in Milwaukee is the final play."

Lau added: "Our grassroots campaign is built to compete in every state and territory and ultimately prevail at the national convention in Milwaukee."

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Marianne Williamson, the mystical author who abandoned her own presidential bid earlier this year and endorsed Sanders, said she sensed pending turbulence.

"[Tom] Steyer has dropped out, now Pete is dropping out," Williamson wrote. "The moderates are consolidating. This is going to be a rocky week. Whichever way your passion lies, this is the moment to drill down. The next two days are everything."

Fox News' Andres del Aguila, Peter Doocy and Paul Steinhauser contributed to this report.