Two top aides to Republican presidential candidate Ben Carson have officially resigned from his campaign.

On Thursday, Carson's communications director Doug Watts announced that he and campaign manager Barry Bennett have quit. He released a statement saying that their resignations are effective immediately.

"We respect the candidate and we have enjoyed helping him go from far back in the field to top tier status," Watts wrote, according to NBC News. "Having just announced raising $23m(illion) for the 4th Q(uarter), more than any other Republican candidate, and passing 1 million contributions and over 600 mm unique donors since March, we are proud of our efforts for Dr. Carson and we wish him and his campaign the best of luck."

Following the announcement, Campaign Finance Chairman Dean Parker said their resignations were "unfortunate" and that they had been "a strategic part of our team." He also told CNN that Bennett is being replaced by Ed Brookover, a senior campaign strategist, while Bob Dees will step up from foreign policy adviser to campaign chairman.

Parker added that Carson had "100 percent confidence in his team."

The two aides resigned just weeks after Carson publicly blamed his advisers for his slipping poll numbers and hinted at a shake-up in his campaign staff.

"Everything is on the table, every job is on the table," he told the The Washington Post in an article published on Dec. 23.

Carson, who at one point was running neck-and-neck with GOP front-runner Donald Trump earlier this year, issued a statement saying that his campaign has entered a "new phase."

"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," Carson said in the statement. "I commend Barry Bennett and Doug Watts for their efforts to help me share my vision for America. Over a year ago, hundreds of thousands of Americans encouraged me to listen to the call and seek the office of president of the greatest nation the world has ever known. I am ready to be president and believe that my unique experience and background is what is needed to heal, inspire and revive America."