He bid farewell to his supporters in a video posted on his campaign website on Tuesday. "Your help was vital," he thanked them.
A formal announcement that he is suspending the campaign, coupled with an endorsement for Mitt Romney, is on the calendar for Wednesday.
By the time he decided to bow out, he had already weathered more crises than appeared survivable.
His entire senior staff quit en masse in the summer of 2011, saying he wouldn't devote enough time to fundraising or campaigning in key early states. He promptly announced he would run a "substantive, solutions-oriented" race, as if he hadn't supervised the hiring of numerous consultants in the preceding months.
When other challengers to Romney faded, Gingrich led the polls late last year before the Iowa caucuses, only to be knocked back by a strong barrage of attack ads financed by a super PAC aligned with Romney.
Somehow, he recovered once more, and won the South Carolina primary in January, before losing Florida and beginning a long, final fade.
It is not clear exactly how long Gingrich has wanted to be president.
He flirted with it in 1995, when he was speaker, and made a joint appearance in the first-in-the-nation primary state of New Hampshire with Clinton to discuss campaign finance legislation.
Years earlier, shortly after taking office in the House in 1979, he said he didn't intend to retire as the ranking member of the House Science and Technology Committee.
Gingrich had lost his first two races for the House, in 1974 and 1976, before his career-defining persistence paid off when a long-term Democratic incumbent retired in 1978, creating a vacancy.
A rare political species at the time, the Republican from Georgia quickly drew notice as a freshman lawmaker in 1979 when he pushed for the expulsion of then-Rep. Charles Diggs Jr. on ethics charges. Diggs, who had been indicted on charges that included taking kickbacks from congressional employees, was censured instead. He resigned his seat the following year.
In the next few years, in the early days of televised House sessions, Gingrich pioneered the practice of excoriating Democrats in speeches delivered at day's end and aired nationally by C-SPAN. Viewers had no idea the speeches were made to an empty chamber until Speaker Thomas P. O'Neill, a Democrat, ordered the cameras to pan the hall to show the rows of vacant seats.
Incensed at the criticism of Democrats, O'Neill said Gingrich had "challenged their patriotism, and it is the lowest thing that I've ever seen in my 32 years in Congress."
Under the rules of the House, O'Neill's remarks crossed the line, and Republicans successfully demanded they be stricken from the record.
Inside the House, Gingrich and his allies created the Conservative Opportunity Society to help build a policy framework on key issues.
Outside Congress, he took over GOPAC in the mid-1980s and used it to build a farm team of future Republican political conservatives.
As speaker, Gingrich made sure the House voted in the first 100 days on each item in the Contract With America, the Republican campaign manifesto from the 1994 election. Never mind that one of the provisions called for limiting House members to six terms in office. By then, he was in his ninth.
His closest associates said he was often the smartest man in the room, and insisted on acting that way.
His ability to outmaneuver others and his understanding of technology were on brilliant display one night just before the Florida presidential primary.
Facing a crushing defeat, he strolled over to a group of reporters in the lobby of a Jacksonville hotel. With a conspiratorial smile, he said a poll coming out in the morning would show him trailing Romney by only 4 points, and having the momentum.
Was that on the record?
It was and, within minutes, virtually the entire press corps had been gulled by a fading candidate into tweeting that a poll of unproven existence showed him with a slim and shrinking deficit.