Ben Carson's presidential campaign manager Barry Bennett and communications director Doug Watts have resigned.
Carson, a retired neurosurgeon, has struggled in the polls since October when he was rivaling Donald Trump for the lead in the Republican presidential race. He has since fallen to 10% in the latest CNN/ORC poll, which ties him for a distant third place with Marco Rubio, behind Trump and Ted Cruz.
His campaign has been marked of late by public sniping between Bennett and Watts with Armstrong Williams, Carson's business manager and sometimes public surrogate who has no official role in the campaign. Williams has criticized Bennett and Watts for not adequately preparing the candidate for public appearances, especially on foreign policy, an issue that has dominated the race in recent months.
Questions about the veracity of Carson's compelling personal story, about his rise out of poverty in Detroit to become perhaps the nation's most widely known neurosurgeon, have also hounded him as he fell in the polls.
Bob Dees, a foreign policy adviser to Carson, is now the campaign chairman. Ed Brookover, a senior strategist, will be the new communications director, Carson's National Finance Chairman Dean Parker said on CNN. Carson's Iowa state director Ryan Rhodes said he will remain with the campaign.
"Barry Bennett and I have resigned from the Carson campaign effective immediately," Watts said in a statement Thursday. "We respect the candidate and we have enjoyed helping him go from far back in the field to top tier status."
Watts added: "We are proud of our efforts for Dr. Carson and we wish him and his campaign the best of luck."
Carson's campaign has raised more than $23 million in the fourth quarter of 2015, his campaign said Wednesday, although it would not say how much cash it has on hand.
Carson last week pushed back against reports a campaign shakeup was imminent, although he did not discount the possibility.
"The key word there is 'may.' We're always going to be looking at it. We're always going to be evaluating how people are performing" Carson told CNN's Don Lemon. "No one is ever 100% guaranteed that they're always going to be there."
Bennett and Watts have been unhappy with Williams' role with Carson, especially as Williams publicly criticized the campaign's struggles, such as the Republican Jewish Coalition speech where Carson repeatedly mispronounced the name of Palestinian group Hamas.
"His campaign has to do a better job at preparing him," Williams said in an interview with CNN earlier this month. "Don't give him speeches at the last minute. It's not only on him, it's on them."
Read: Ben Carson campaign at war with itself
Responding to those comments, Bennett said of Williams: "I don't think he is always helpful. You always defend your candidate."The resignations were first reported Thursday by the Des Moines Register