Three of Republican U.S. presidential candidate Ben Carson's top aides have resigned, causing a big shake-up in his campaign less than five weeks before voters in the Midwestern state of Iowa begin the 2016 nominating process.
Carson, a conservative Christian, once rivaled front-runner Donald Trump in the quest for the Republican nomination for the White House, but has been struggling in the polls in recent weeks.
Carson's campaign manager, Barry Bennett; his deputy campaign manager, Lisa Coen; and his communications director, Doug Watts, all resigned Thursday, citing frustration with the influence of the retired neurosurgeon's business manager and questioning the candidate's readiness for the White House.
Carson was rivaling Trump for the lead in the Republican race in mid-October, but he has since fallen to 10 percent in the latest CNN/ORC poll, which ties him for a distant third place with Senator Marco Rubio, behind Trump and Senator Ted Cruz.
His campaign has been marked by public sniping between Bennett and Watts with Armstrong Williams, Carson's business manager and close friend, who has no official role in the campaign. Williams is a syndicated columnist and radio and TV talk-show host.
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.
Carson's foreign policy credentials were called into question, especially after he repeatedly mispronounced Hamas as "hummus" while addressing a group of prominent Republican Jews.
Carson's campaign released a statement Thursday describing staff changes as "enhancements'' that "will shift the campaign into higher gear.''
Retired U.S. Army Major General Robert Dees, who has been advising Carson on foreign policy and military affairs, will serve as campaign chairman. Ed Brookover, formerly a senior strategist, will serve as campaign manager.