President Donald Trump. Reuters/Kevin Lamarque

Democratic Rep. Mike Quigley, who sits on the House Intelligence Committee, said the public would want him to "go full throttle" if they saw what he had seen during the investigation into Russia's interference in the 2016 presidential election.

The committee's probe "is closer to its infancy than conclusion," Quigley said during an event moderated by Renato Mariotti, a longtime federal prosecutor, in Chicago on Thursday.

And working with the committee's chairman, Republican Rep. Devin Nunes, "has been much more difficult and troublesome" since the Russia investigation began, Quigley said.

He said that while Nunes stepped aside from leading the probe in April, he had "not fully given up" the responsibilities of that role.

"For instance, he insisted that he still be the one who signs the subpoenas," Quigley said. "So who's the boss? You can't have two people running the investigation on the House side. The subpoena power is extraordinarily important ... This has created just one issue we have in moving forward."

Nunes earlier this month threatened to hold Attorney General Jeff Sessions and FBI Director Chris Wray in contempt of Congress if they did not respond to a subpoena for documents relating to the dossier alleging ties between President Donald Trump and Russian officials.

He also subpoenaed the CIA, the FBI, and the National Security Agency earlier this summer for more details about why Obama administration officials requested the unmasking of Trump associates last year.

Quigley said Nunes was "not the only" Republican on the committee creating problems.

"I'm there as we're questioning witnesses — and someday these transcripts will be made public," he said. "Many of you are going to say, 'What the hell are they doing?' They seem to be taking over the role of a second attorney for the witness testifying before us. And it's conflicting, and it's difficult. It's difficult enough as it is to do this job when you're running into all of these obstacles."

Rep. Mike Conaway, who took over the committee's Russia investigation after Nunes stepped aside, was not immediately available for comment.

Quigley also lamented the lack of unity in the congressional Russia probes, both between the House and the Senate and between Democrats and Republicans, saying it was "conceivable that Republicans and Democrats would have separate reports" if they issued their findings of the investigation today.

"And that's very unfortunate," Quigley said.

"I was old enough to understand — and watch — Watergate," he said. "This is so much more important. Because I believe that if you had seen what I have seen, you'd want me to go full throttle. Anything that makes the analysis of this by Congress, or any other investigators, inconsistent in any way ... reduces how important this is."

Quigley added that he was very concerned that the Russia investigation led by the FBI's special counsel, Robert Mueller, "could be shut down."

"We've come very close to the edge" of a "constitutional crisis," he said, pointing to Trump's controversial pardon of Joe Arpaio, the former Arizona sheriff, late last month.

"The president always foretells what he's out to do by messaging to his base," Quigley said. "So when you saw him start to criticize Sessions, you got a clue that he wanted to get rid of him.

"My message is to let everyone in the public know why this matters," he said. "The American public needs to know everything it possibly can."