Republican presidential candidate Ben Carson lost another top campaign adviser on Thursday, as his organization shows more signs of disorder just ahead of the first GOP debate of 2016, as well as early state voting in Iowa and New Hampshire.

Carson's national finance chairman Dean Parker resigned Thursday amid questions about his use of campaign funds as well as his treatment of donors. Carson appointed the Mobile, Ala., tech industry entrepreneur in May to head up the campaign's fundraising efforts. Since joining Carson's bid for the Republican nomination, campaign insiders said that Parker has incurred unnecessary expenses and paid high fees to consulting staff, including his own $20,000 monthly salary for what is typically an unpaid role, Politico reported.

The Carson team tried to put a positive sheen on the departure, which shows continued stress within the campaign. "Dean has been a valued member of my campaign team and a trusted friend; I appreciate and honor Dean's tireless efforts on behalf of saving America," Carson said in a statement, CNN reported. "Our significant fundraising success has been due, in large part, to Dean's dedication and commitment to 'We the People.'"

Although the campaign raised a sizable $23 million in the fourth quarter of 2015, it has refused to say how much cash it still has on hand.

"I recognize that nothing is perfect," Carson said in an interview with the Associated Press in December. "And, yes, we've had enormous fundraising, but that requires that you be efficient in the way you utilize the funds. And, yes, we are looking at all those things."

Parker's resignation comes just weeks after former campaign manager Barry Bennett and former communications director Doug Watts resigned Dec. 31. Bennett's deputy, Lisa Coen, also resigned. Those resignations were precipitated by Carson's warnings that major changes were coming to the campaign staff.

Earlier this week, a new display of declining support for Carson emerged as all five paid staffers in the New Hampshire office of the super PAC supporting him quit their posts. The staffers left on Sunday to become volunteers for Ted Cruz after growing disappointed with Carson whom they say hasn't spent enough time in the early primary states, according to MMUR

"We hold Dr. Carson in the highest regard," said Jerry Sickles, spokesman for the super PAC staff, according to Boston.com "This is a man we revere, but we think it is important that our party nominate a conservative and get behind a single conservative who can win, and we strongly believe that candidate is Ted Cruz."

Carson has shown a steady decline in the polls since peaking in November. According to national averages compiled by RealClear Politics, Carson is polling at a 9.0 percent after nearly reaching 25 percent in early November.