By Caroline Kelly and Liz Stark, CNN

(CNN) -- Former Trump campaign national co-chairman Sam Clovis broke his silence on the possible FBI confidential source on the Trump campaign during recent appearances on an Iowa radio show, telling listeners he was concerned that the source had been trying to plant an audit trail for investigators to later use to justify surveillance warrants.

Clovis said the two had met over coffee on Sept. 1, 2016, at a DoubleTree hotel in Arlington, Virginia.

"The meeting was very high level; it was like two faculty members sitting down in the faculty lounge talking about research," Clovis said Monday on the "Simon Conway Show." "There was no indication or no inclination that this was anything other than just wanting to offer up his help to the campaign if I needed it."

Clovis recounted sitting in the lobby with the professor, coffee and notebook in hand, but not taking any notes. "I didn't have any notes on the meeting because there must not have been anything substantive that took place. Because it was nothing new," Clovis explained.

He continued: "It was an academic meeting. It was not anything other than him talking about the research that he had done on China. That was essentially what the discussion was about. We already had a lot of China people involved."

Clovis said he and the confidential source exchanged four emails, with the source leveraging his previous meeting with former Trump campaign foreign policy adviser Carter Page as a way to establish a networking connection with Clovis.

Clovis contradicted his lawyer's later statement to The Washington Post, which claimed he did not know of the source's relationship with Page at the time and was "unsettled" upon learning about it.

"(He) had met with Carter Page, he used that as the bona fides to get an appointment with me," Clovis said, "and then I think he used my meeting as a bona fides to get a meeting with George Papadopoulos."

"The thing that's unsettling to me," Clovis explained, was the source's apparent motivation "to establish an audit trail from the campaign or somebody associated with the campaign, back to those Clinton emails -- whether or not they existed, we don't know."

"The FBI and the Department of Justice, they were attempting to create something that did not exist and there was no evidence that it existed," he added, "to create an audit trail that would lead investigators on something. Then they would have justification to go back for their FISA warrants and all their other things."

The Foreign Intelligence Surveillance Court oversees requests from the government for surveillance warrants on foreign individuals under the Foreign Intelligence Surveillance Act.

Clovis argued that now the Steele dossier, a compilation of confirmed and unconfirmed reports on then-candidate Donald Trump's alleged ties to Russia produced by former British spy Christopher Steele, is being used instead as "the principal means to create probable cause to get FISA warrants on Carter Page."

Clovis said the professor followed up with an email containing some of his research materials, but "to this day, I have not read a single one of them."

Clovis previously played coy about the identity of the source. "I think the proper term is not informant," he said during a guest host appearance on the radio show that aired last week. "I'm not going to name the individual, I know exactly who it is ... but I will say this: That person had nothing to do with the campaign. They were not part of the campaign."

Clovis' comments came amid rising tensions between President Trump and the Justice Department over reports that the FBI dispatched a confidential intelligence source to meet with Trump aides during the 2016 campaign. Trump has suggested on Twitter that an FBI source was "embedded" in his campaign, and on Sunday, the President tweeted that he would demand that the Justice Department investigate whether the FBI had "infiltrated or surveilled" his campaign for political purposes.

CNN has previously reported that a confidential source was not planted inside the Trump campaign to provide information to investigators, according to US officials.

Later in the appearance, Clovis confirmed that he was questioned by special counsel Robert Mueller's team, had testified before Mueller's grand jury and had given interviews to the House and Senate Intelligence committees -- what he called "the big four."

Clovis withdrew his nomination for a top job at the Department of Agriculture following scrutiny of his contacts with Papadopoulos.

Clovis described the personal toll that the Russia investigation has wreaked on him, saying it has "damaged" his reputation with "personal attacks." He also said he has incurred "thousands and thousands of dollars in legal fees."