Sen. Ron Johnson, R-Wis., said on Tuesday he had an "informant" corroborate reports concerning the existence of an FBI "secret society" working to undermine President Trump.

"What this is all about is further evidence of corruption, more than bias, but corruption at the highest levels of the FBI," Johnson told Fox News' Bret Baier.

"Now a secret society? We have an informant that's talking about a group that were holding secret meetings off site. There is so much smoke here, there is so much suspicion," the senator continued.

Johnson would not expound upon his answers when pressed by Baier for details regarding the "informant," simply adding it was an issue congressional investigators would have "to dig into."

References to an anti-Trump "secret society" within the agency emerged this week with the release of more text messages between FBI officials Peter Strzok and Lisa Page, former members of special counsel Robert Mueller's Russia probe.

"There is a text exchange between these two FBI agents, these supposed-to-be fact-centric FBI agents saying, 'Perhaps this is the first meeting of the secret society,'" Rep. Trey Gowdy, R-S.C., told Fox News Monday, referring to a missive sent between the pair the day after the election.

Johnson on Tuesday also called for the appointment of a special counsel to examine allegations of inappropriate behavior at the FBI.

"Robert Mueller used to run the FBI. He's in no position to do an investigation over this kind of misconduct," he said. "So I think at this point of time we probably should be looking at a special counsel to undertake this investigation, but Congress is going to have to continue to dig."

The Justice Department is currently reviewing why five months worth of messages between Strzok and Page are missing.