Gingrich is reportedly set to announce he's dropping out of the race in a week, ending a bid for president remarkable for its outward displays of arrogance, delusion and bitterness.
He all but conceded the nomination to Mitt Romney in an appearance in North Carolina on Wednesday morning, just hours after the front-runner swept five state primaries.
Gingrich placed dead last in all but one of those contests, Delaware, finishing behind libertarian congressman Ron Paul, who's remaining in the race.
"It's pretty clear Gov. Romney is going to be the nominee," Gingrich told supporters in Cramerton, N.C.
"I think you have to at some point be honest with what's happening in the real world, as opposed to what you'd like to have happened. I think obviously that I would be a better candidate, but the objective fact is the voters didn't think that.... And I also think it's very, very important that we be unified."
Gingrich, 68, said an announcement on the future of his campaign was forthcoming. Several news outlets report the former speaker of the House of Representatives plans to formally announce he's dropping out on Tuesday after a farewell tour of sorts through North Carolina.
"We're working out the details of our transition and we'll have information for the press in the next couple of days," Gingrich said, adding he'd continue to campaign in the so-called Tar Heel State this week "as a citizen."
It marks the beginning of the end of Gingrich's topsy-turvy run for president, which saw him recover from a campaign in utter disarray last summer to become Romney's chief rival heading into the Iowa caucuses.
But Romney's attack ads against him leading up to the first contest of the primary season unleashed a Gingrich described by conservative New York Times columnist Peggy Noonan as "the Pillsbury Doughboy on a rampage."
He rarely let go of his rage at Romney, repeatedly branding him "fundamentally dishonest" and vowing to fight to the bitter end to deny him the nomination.
A month ago, Gingrich said he had no intention of dropping out of the race and would swipe the crown from Romney in a brokered convention, a highly unlikely scenario that could only happen if the front-runner failed to get the support of 1,144 delegates.
Romney's on track to get to 1,144 by late May.
Gingrich's lofty ideas — he once acknowledged they were "grandiose" — and his often snide, adverb-laden pontifications on the campaign trail provided some of the biggest unintended laughs of the Republican race.
He was roundly mocked, for example, for his insistence that he'd build an American colony on the moon if elected president — ridicule that some reports said wounded him personally.
His frequent defence of the sanctity of marriage as he opposed same-sex unions was also the subject of mockery. Gingrich has left two wives for other women, and is now married to Callista Gingrich, his third spouse and former mistress.
A skilled debater, Gingrich also had a tendency to over-state doomsday scenarios regarding terrorists, Iran and al-Qaida as he out-debated his opponents in a series of televised showdowns that helped him rise in the polls.
"All of us are more at risk today, men and women, boys and girls, than at any time in the history of this country," he said.
A few minutes later, when asked what word best described him, Gingrich replied with no hint of irony: "Cheerful."
There were also titters when the man who considers himself a towering intellect — and has compared himself, straight-faced, to Charles De Gaulle, Thomas Edison and the Wright brothers — attempted to show his southern bona fides by wearing a bass fishing shirt and talking about gun racks when he campaigned in the Deep South.
Gingrich, in fact, has lived in a swank Virginia home across the Potomac River from the U.S. capital for years, despite portraying himself as a D.C. outsider throughout his run for president.
His unlikely run for president came almost 15 years after he was literally run out of his job as speaker by fellow Republicans fed up with his arrogant management style. His ouster came just four years after Gingrich lead the so-called Republican Revolution in 1994's mid-term elections that saw the party take control of the House for the first time in 40 years.
His posh tastes almost sank his campaign last spring when it was revealed he had a massive expense account at Tiffany's, apparently to provide trinkets for Callista Gingrich. His aides quit en masse when he travelled to the Greek islands at his wife's behest just as the campaign was kicking off.
But he persevered, becoming a darling of social conservatives as the Iowa caucuses approached. In the end, however, he managed to win just two of 43 primaries — South Carolina and Georgia, where he served as a U.S. congressman for two decades.
He also exits the race with his campaign more than US$4 million in debt.
In perhaps the surest sign his campaign is over, Gingrich uncharacteristically praised Romney on Wednesday after months spent sniping at him for his deep pockets.
"You have to give him some credit," he said.
"This guy's worked six years, put together a big machine, and has put together a serious campaign."