President Trump challenged the Justice Department and FBI early Monday over why the agencies have not given Congress all requested documents related to an FBI informant in contact with members of his campaign in 2016.

The president’s comments come ahead of the latest deadline set by House Intelligence Committee Republicans for the agencies to turn over key documents tied to the start of the Russia investigation.

“I have tried to stay uninvolved with the Department of Justice and FBI (although I do not legally have to), because of the now totally discredited and very expensive Witch Hunt currently going on. But you do have to ask why the DOJ & FBI aren’t giving over requested documents?” Trump tweeted early Monday.

The FBI sent a classified letter to House Intelligence Committee Chairman Devin Nunes, R-Calif., on Friday in response to their requests. Nunes has since set a 5 p.m. ET Monday deadline for Deputy Attorney General Rod Rosenstein to answer questions about informants used in 2016.

Nunes on Monday slammed the FBI as “swampy” for waiting “until the stroke of midnight” to send the latest letter.

"Are you running spies into Senate campaigns, House members campaigns?" Nunes asked on "Fox & Friends." "This needs to be cleared up. The DOJ and FBI are on a very slippery slope."

The letter said its confidential explanation outlined whether the “FBI utilized confidential human sources prior to the issuance of the Electronic Communication initiating that investigation,” adding that it had forwarded House Republicans’ requests for summaries and transcripts of any conversations between Trump campaign officials and informants to the Office of the Director of National Intelligence.

Nunes said on “Fox & Friends” that he would meet with Director of National Intelligence Dan Coats on Monday.

“I think the American people are beginning to see what we’ve been after for a very long time, and that is—is it common, or does it happen, that counterintelligence agencies in this country…are they used to target campaigns?” Nunes said on “Fox & Friends” Monday. “I would think most of the American people, including most people in politics, would be very, very worried if the FBI was running informants into our campaigns.”

Allegations that the FBI attempted to infiltrate the Trump campaign prior to the initiation of the formal Russia probe on July 31, 2016, have roiled Washington, amid numerous findings of anti-Trump bias among top officials in the agency.

In one instance, over drinks at a high-end London hotel in the summer of 2016, an alleged FBI informant reportedly asked former Trump adviser George Papadopoulos if he knew anything about Russian attempts to influence the 2016 election.

But Democrats said after a DOJ briefing in May that there was no evidence to suggest that federal law enforcement actually placed a spy in the campaign.

The FBI also told Nunes that it is still working to produce documents related to Christopher Steele—the former British spy who authored the salacious and unverified anti-Trump dossier.

“Christopher Steele was hired by the Democratic Party and the Hillary Clinton campaign to dig up dirt on Trump and his associates. That made its way to the FBI and to the State Department,” Nunes said. “At the same time, it appears you have multiple people in a six-week period from April to June that are making offers of selling some kind of dirt on Hillary Clinton from Russia to the Trump campaign…or maybe the FBI was running people in.”

Nunes added: “This is a legitimate investigation.”

Fox News' Gregg Re contributed to this report.