Rick Tyler, the former U.S. House speaker's spokesman, said that he, campaign manager Rob Johnson and senior strategists had all quit, along with aides in the early primary and caucus states of Iowa, New Hampshire and South Carolina.
Other officials said Gingrich was informed that his entire high command was quitting in a meeting at his campaign headquarters in Washington. They cited differences over the direction of the campaign.
Scott Rials, a longtime aide who joined the departure, said he doubted Gingrich's ability to win the nomination.
"I think the world of him. But at the end of the day we just could not see a clear path to win, and there was a question of commitment," Rials told The Associated Press.
Gingrich, a former Georgia congressman, has long been viewed by even his closest allies as a fountain of policy ideas but a man who is unable to avoid speaking in ways that spark unwelcome controversy.
The former speaker told the group he intended to stay in the race, the officials added. They declined to be identified by name, saying they were not authorized to discuss private conversations.
Gingrich could not be reached for comment immediately.
Even before the sudden departures, Gingrich's campaign was off to a notably rocky start. Within days of formally announcing he would run, he was assailed by conservatives for criticizing a plan to remake Medicare that Republicans pushed through the House.
He called the author of the plan, Rep. Paul Ryan of Wisconsin, to apologize but did not back off his objections.
Within days, he had dropped from sight, embarking on a cruise to the Greek Isles with his wife, Callista, while rivals for the Republican nomination kept up their campaign appearances.
He returned to the United States earlier in the week to confront a rebellion that had been brewing for some time among the senior echelon of his campaign.
While Gingrich told his now-departed aides he would remain in the race, he faces formidable obstacles in assembling a new team in time to compete in a campaign that's well under way.
Most immediately, he is scheduled to participate in a debate next Monday in New Hampshire.
Johnson and another key aide, strategist David Carney, joined Gingrich's campaign after working as senior political staff members for Texas Gov. Rick Perry.
Perry ruled out running for the White House earlier in the year, but more recently has said he might reconsider. It was not known whether his former aides were interested in returning to him.
Gingrich, 67, last served in public office more than a decade ago. He resigned as speaker of the House after two terms following an unexpectedly close mid-term election in 1998 in which Republicans gained far fewer seats than he had predicted.
In the years since, he has established a virtual one-man think tank, publishing books and speaking publicly.