Dean Parker, the national finance chair for Ben Carson's presidential campaign, resigned Thursday, capping off a recent string of top aides that have departed the former neurosurgeon's 2016 team since last year.

The campaign announced Parker's resignation in a statement Thursday, just as the aide comes under fresh criticism for his spending decisions from the campaign's allies and donors.

"Dean has been a valued member of my campaign team and a trusted friend," Carson said in the statement. "I appreciate and honor Dean's tireless efforts on behalf of saving America."

Get Breaking News Delivered to Your Inbox

The Republican candidate, whose previous front-runner status has given way with the rise of Ted Cruz in early-nominating states, attributed his campaign's hefty fundraising haul to his departing finance chair.

"Our significant fundraising success has been due, in large part, to Dean's dedication and commitment to 'We the People,'" Carson added.

Parker leaves Carson's team amid increased scrutiny over his handling of campaign funds.

Early Thursday, Politico cited campaign insiders when reporting that Parker had racked up unnecessary expenditures for the campaign, including large payouts to inexperienced consultants. Parker himself recently began earning a $20,000 monthly salary, which the former Carson aide claimed he only began collecting this month, according to Politico.

Parker, a tech entrepreneur from Mobile, Alabama, refuted the attacks on his campaign spending as untrue and called his time with Carson a "great honor."

"While current allegations towards me are misrepresentations, my primary goal is to help Dr. Carson save our nation," Parker said in a statement. "I am excited about the growing momentum behind him and look forward to even greater days ahead."

Carson will participate on the main stage in Thursday's GOP debate, the last Republican debate before the nation's first nominating contests in Iowa on Feb. 1.