The super PAC supporting Gov. Ron DeSantis of Florida in his presidential campaign, which has seen a series of changes in the last month, went through another shake-up this week when it fired its new chief executive officer who had stepped in just nine days earlier, according to two people briefed on the matter.

Kristin Davison, who was appointed chief executive after serving as chief operating officer of the group, Never Back Down, was fired and replaced by Scott Wagner, a longtime friend of Mr. DeSantis who was also named chairman after the departure of another close DeSantis ally, Adam Laxalt, who resigned from that role just a week ago.

Ms. Davison was not alone in being fired, according to the people briefed on the matter. A spokeswoman for the group, Erin Perrine, was dismissed, they said, with more departures possible.

The changes come as the primary enters the intense final weeks before the first nominating contest, and as Mr. DeSantis was in the Iowa celebrating the final stop in his tour of the state’s 99 counties — an achievement made possible by the organizational muscle and money of his allied super PAC, which is suffering its third round of upheaval in recent weeks.

It was unclear who was behind the dismissals or the cause. Ms. Davison and Ms. Perrine did not respond to requests for comment. Ms. Davison’s departure was first reported by Politico.

“Scott Wagner will now serve as chairman of the board and interim C.E.O. of Never Back Down,” said Jess Szymanski, a spokeswoman for the group. “Never Back Down has the most organized, advanced caucus operation of anyone in the 2024 primary field, and we look forward to continuing that great work to help elect Gov. DeSantis the next president of the United States.”

The latest shake-up caps a turbulent period at Never Back Down, which was formed earlier this year, well before Mr. DeSantis became a candidate for president, and sought to take on a number of functions that a campaign traditionally performs, such as building out a field operation in several states.

Recently, the group’s senior officials engaged in internal battles as close allies of Mr. DeSantis based in Tallahassee created a new outside group, Fight Right, to which Never Back Down was expected to transfer $1 million. The fact of that transfer, which was to fund attacks on Mr. DeSantis’s closest rival in the presidential primary, Nikki Haley, was called “exceedingly objectionable” by another Never Back Down official, Ken Cuccinelli, in an email to colleagues.

On the eve of Thanksgiving, the group’s chief executive officer since it began, Chris Jankowski, resigned, saying he had issues that went “well beyond” strategic differences. Five days later, Mr. Laxalt left, saying in a resignation letter that it was time to spend time with his family, having joined the group right after his own unsuccessful Senate campaign in Nevada ended last year.

It was unclear if those events related to the firings, which occurred shortly afterward.

Ms. Perrine and Ms. Davison both work with the group’s main strategist, Jeff Roe, at his company, Axiom Strategies. Mr. Roe filled a number of roles at Never Back Down with Axiom employees early on. Mr. Roe had a dispute with Mr. Wagner right before Fight Right was created during one of the group’s meetings at its Atlanta offices, according to two people with knowledge of the events.

Meanwhile, the new super PAC, Fight Right, has been welcomed by the DeSantis campaign. Mr. DeSantis and his wife are said to have been troubled by Never Back Down’s advertising for many months. While campaigns are prohibited from directly coordinating with super PACs, Mr. DeSantis’s campaign manager, James Uthmeier, wrote in a memo last Monday that Fight Right would provide “welcomed air support” with television ads. The memo suggested Never Back Down would focus on its “field operation and ground game.”

“Fight Right’s mission could not have come at a better time,” Mr. Uthmeier wrote.