Washington (CNN) The top Democrat on the Senate Intelligence Committee said Friday that it would be "uncharted territory" if President Donald Trump tried to fire the special counsel investigating Russian election meddling and possible collusion by the Trump campaign.

The statement comes a day after reports that Trump called for Mueller's firing in June.

"I think if the President had gone through with this, or tries to go through with it on a going forward basis, we're into uncharted territory," Sen. Mark Warner of Virginia told CNN's Jake Tapper on "The Lead" Friday. "We're into the real question of the fundamentals of our democracy."

Trump denied the reports , describing on Friday them as "fake news."

"These are not the actions of an individual who doesn't have something to hide," Warner said. "The President keeps saying, 'There's no there, there.' Well, if there's no there, there, let these investigations, including our bipartisan Senate intelligence investigation, finish our job."

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