He said Attorney General Jeff Sessions was doing President Trump's bidding to distract from the Russian Federation probe. None of this has made us waver in our mission to help people.
The investigation, led by the FBI field office in Little Rock, Arkansas, is being overseen by the USA attorney's office in the state, according to the source.
While previous presidents have generally stayed out of Justice Department investigations, Mr. Trump has repeatedly called for prosecutors to investigate or imprison his political rivals.
Reports of a new Justice Department investigation into the Clinton Foundation caught the attention of many who have been demanding a probe into the organization's activities for years.
Critics have accused the Clinton family of using the foundation to enrich themselves and give donors special access to the State Department when Hillary Clinton was secretary of state. There were also concerns within the Justice Department about the close proximity to the election, CNN reported at the time.
"These donations came from all 50 states, and I assure you these donors took the donation as a reduction in income, therefore a reduction in their taxes on federal and state income tax, and they did that in states where the Clinton Foundation was not a bonafide charity, and the feds want to know about it", he told FOX Business' Liz MacDonald on "Risk & Reward".
Republican lawmakers had called on Attorney General Jeff Sessions in July and again in September to explore various Clinton Foundation dealings, as well as other matters, by appointing a special counsel to look into Clinton-related issues.
United States media outlets including the New York Times in recent years have scrutinised the Clinton Foundation.
The FBI is investigating allegations of corruption connected to the Clinton Foundation while Hillary Clinton was secretary of state. It was set up in 1997 by then-President Bill Clinton.
Nick Merrill, Clinton's chief spokesman, slammed the FBI's decision to re-open the case as "disgraceful", contending it is a distraction from collusion allegations facing Trump.
"The goal is to distract from the indictments, guilty pleas, and accusations of treason from Trump's own people at the expense of our justice system's integrity", he said.
The debate he was referring to the second presidential debate between Trump and failed Democratic nominee Hillary Clinton in October 2016.