Cheryl Senter/Associated Press

Newt Gingrich’s campaign manager and a half-dozen senior advisers resigned on Thursday, two aides said, dealing a significant setback to his bid for the Republican presidential nomination and severely complicating his hopes for a political comeback.

Mr. Gingrich’s campaign manager, Rob Johnson, his longtime spokesman, Rick Tyler, and advisers in Iowa, New Hampshire and South Carolina stepped down together after a period of deep internal disagreements about the direction of the campaign.

Mr. Gingrich, a former House speaker who has been fighting to regain his political footing after a rough campaign roll-out last month, had been absent from the campaign trail for about two weeks on what aides had described as a long-planned vacation. He made his return on Wednesday in New Hampshire, a day before the resignations were announced.

In a statement on his Facebook page Thursday afternoon, Mr. Gingrich said he would not abandon his presidential campaign. He said that his next public appearance would be this week in California at an event sponsored by the Republican Jewish Coalition.

“I am committed to running the substantive, solutions-oriented campaign I set out to run earlier this spring,” Mr. Gingrich wrote. “The campaign begins anew Sunday in Los Angeles.”

The resignations were first reported on Thursday afternoon by The Associated Press. The two aides, speaking on condition of anonymity, confirmed the resignations to The New York Times. The aides said the future of Mr. Gingrich’s campaign was not immediately clear.

The defections included several veteran Gingrich political advisers as well as recently hired aides. The list, according to two aides, included David Carney, a political strategist based in New Hampshire; Sam Dawson, a strategist; Katon Dawson, a consultant in South Carolina; and Craig Schoenfeld, a consultant in Iowa.

The shake-up comes as the field of Republican presidential candidates remains unsettled. Two of the advisers to Mr. Gingrich also have been top political aides to Gov. Rick Perry of Texas, who is taking a second look at exploring the Republican presidential nomination.

In his return to the campaign trail on Wednesday, Mr. Gingrich portrayed his time off as a chance to “get away and think” – not about his viability as a candidate, but about important national issues.

Mr. Gingrich had been on a cruise with his wife, Callista, in the Greek isles, a trip his campaign said had been planned before he announced his candidacy last month. While passengers enjoyed port calls at Rhodes and Mykonos, according to the ship’s itinerary, the Seabourn Odyssey, Mr. Gingrich said he wrote two policy speeches.

“I don’t know how other people work,” Mr. Gingrich said. “To have a major breakthrough in policy, you have to be able to stop and think.”

Several advisers pleaded with Mr. Gingrich not to go on the trip, an aide said, but Mrs. Gingrich wanted to go. “We have a spouse who controls the schedule,” said the aide, speaking on condition of anonymity to discuss the internal workings of the campaign.

An aide to Mr. Gingrich said that the resignations followed a conference call on Wednesday in which top campaign officials confronted Mr. Gingrich over his lack of focus. They demanded that he spend 90 percent of his time campaigning in three states — Iowa, New Hampshire, South Carolina — and curtail distractions like screenings of his documentaries.

His trip to New Hampshire on Wednesday, for example, was built around promoting a documentary he produced with his wife.

Campaign managers were also worried about expenses. In a three-day swing through Iowa last month, Mr. Gingrich spent $40,000 on a chartered Citation 10 jet, the aide said.

Despite the free spending, money was tight, because traditional donors to Mr. Gingrich had told him they would not support his run. The bad publicity over a gaffe Mr. Gingrich made about Medicare on “Meet the Press” and the revelation that he once owed Tiffany a six-figure sum had also discouraged donations.

Mr. Gingrich, 67, formally announced his candidacy on May 11. Within days, he was engulfed by Republican criticism over describing the proposal to privatize Medicare – the centerpiece of the House Republican budget plan – as “radical change” and a form of “social engineering.”

He also struggled to answer questions about why he and his wife had a line of credit of up to $500,000 for jewelry purchased at Tiffany & Company.

Mr. Tyler, the long-serving press aide to Mr. Gingrich, said he and other advisers had become especially worried with the candidate’s decisions about how and when to campaign.

“The team that left had a different idea of what it would take to win,” Mr. Tyler said in a brief telephone interview on Thursday. “Everyone agreed there is a path to victory, but there was a disagreement about what that was.”

In particular, Mr. Tyler said that he and other senior advisers believed that a significant investment of on-the-ground time in the early-voting states of Iowa and New Hampshire was needed to repair the damage from Mr. Gingrich’s stumbles last month.

“Take all those things together, you are in a handicapped position,” Mr. Tyler said. “Given the state of the campaign and the press, the campaign needed to recover. That was going to require a lot of time in the states. The schedule did not reflect what I would say was required.”

Mr. Tyler has worked for Mr. Gingrich for years, managing his contacts with the news media through his 2007 flirtation with a presidential campaign, then serving as his chief spokesman during the current White House bid.

Mr. Tyler said that Mr. Gingrich sometimes “puts unnecessary stumbling blocks in front of himself,” but he added that Mr. Gingrich was not lazy and that he might still be able to recover politically.

“I hope he does well. He’s a great intellect,” Mr. Tyler said. “It’s sad. But it’s time to move on.”

Michael D. Shear contributed reporting.