Republican National Committee Chairman Reince Priebus sent a letter to the Clinton Foundation Monday asking the charity to release voluntarily its correspondence with the State Department while Hillary Clinton served as secretary of state.

"In defending her interactions, Secretary Clinton has maintained that while 'there's a lot of smoke … there's no fire,' or evidence of Clinton Foundation donors receiving special treatment," Priebus wrote in the letter to Donna Shalala, president of the charity.

"Because we know that federal records are incomplete through Mrs. Clinton's failure to comply with federal records retention policies, the records in the foundation's custody have the unique ability to buttress or undercut her assertions on this matter," he added.

The RNC chairman's call came just days after the State Department shot down requests to release half of Clinton's official schedules before the election. Agency officials have indicated they will withhold documents in other open records lawsuits until after the election, including documents requested by the RNC.

The Clinton Foundation has come under fire this month in light of several new batches of emails that show donors receiving favorable treatment from State Department staff.

Clinton and her allies have pointed to the charity's volume of work in defense of its actions during the Democratic nominee's time in the administration.

However, Clinton's husband stoked speculation that the contact between State Department and foundation officials was inappropriate when he announced earlier this month that the charity would refuse foreign and corporate donations if Clinton wins the White House.

Priebus said Monday that a third party should scour the Clinton Foundation's email records to identify the ones related to State Department business in order to deny charity employees the opportunity to withhold any that could reflect poorly on the Democratic nominee.