This story was updated at 3 p.m. ET

Two top staffers for Ben Carson's presidential campaign have resigned, an ominous sign for the struggling Republican's White House hopes just a month before voting begins.

Campaign manager Barry Bennett and communications director Doug Watts have both stepped down, something the campaign called "enhancements" to "shift the campaign into a higher gear."

Retired Army Major General Bob Dees will take over as campaign trail while Ed Brookover, former a senior strategists, will be the new campaign manager.

"As we enter a new phase of the campaign cycle, it is necessary to invigorate my campaign with a strategy that more aggressively shares my vision and world-view with the American people. I commend Barry Bennett and Doug Watts for their efforts to help me share my vision for America," Carson said in a statement.

The news comes after Carson himself promised a campaign shake-up to right the once-insurgent candidate's ship.

But according to the Washington Post's Robert Costa, the exits were instigated by Bennett and Watts themselves, not Carson, after tensions with Armstrong Williams, the neurosurgeon's longtime friend and business manager, reached a breaking point.

In an interview with The Hill, Bennett blamed Williams for much of the campaign's turmoil and predicted others would soon follow him.

"I called Ben this morning...and explained to him the root of the problem is that you told me Armstrong is not involved in the campaign but he clearly is," Bennett said. "My frustration level is boiling over so I told him I think it's best that I leave."

But Williams played down his clashes with the top staffers in an interview with NPR and said that under the leadership of Bennett and Watts, Carson rose to nearly topple Donald Trump in the polls.

"I would never have characterized it as tension. I think in families, in corporations, in franchises sometimes we all have our perspectives from our experiences on how things should be set up and we always discuss those in very respectful manners, and at the end of the day we're on the same page," Williams said. "Especially when you're in an ever-changing political campaign with a presidential candidate, it is expected that there will be some tension, but that's part of the process."

Williams was optimistic that the new changes could invigorate the Carson campaign heading into the final stretch, saying the Republican had already been showing a deeper depth on foreign policy and that voters were coming back around to his low-key demeanor.

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