Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, warned on Wednesday that President Trump revoking former CIA Director John Brennan's security clearance could set a precedent for taking similar action against special counsel Robert Mueller.

"I worry whether this precedence will lead to the president trying to take away Mueller and his whole team's security clearances. This is clearly another effort to silence critics and not allow the Mueller investigation, and for that matter our Senate intelligence community investigation, to get to the bottom of this," Warner said, referring to his committee's Russia investigation as well as the federal inquiry.

The Virginia Democrat was addressing reporters on Capitol Hill after White House press secretary Sarah Sanders announced the move against Brennan and read a statement from Trump, citing the "risks posed by his erratic conduct and behavior." Brennan has been a vocal critic of the president, and he was the first in a list of ex-top officials-turned-Trump-critics whom the Trump administration has taken action against.

[Michael Hayden: Revoking Brennan’s security clearance appeared to be a warning to other former officials]

Those individuals still under review include former FBI Director James Comey, former national security adviser Susan Rice, former Director of National Intelligence James Clapper, former Deputy FBI Director Andrew McCabe, and former Deputy Attorney General Bruce Ohr, who is still employed at the Justice Department.

Warner decried Trump for calling Brennan's actions "erratic" and suggested that the commander in chief needs to "look in the mirror."

While noting that Trump's actions reminded him of former President Richard Nixon's tactics to silence his enemies, Warner suggested the White House was attempting to distract from bad press coming from the trial of former Trump campaign manager Paul Manafort and the bombshell accusations made by former White House aide Omarosa Manigault Newman.

"It appears that this is a White House that feels under siege because of his former campaign manager's trial and obviously some of the issues with his former staffer, Omarosa. This is an attempt to distract the American public from those items that this White House faces on a daily basis," Warner said.

The Manafort trial, focusing on tax and bank fraud charges, reached its 12th day on Wednesday. It is the first trial to stem from Mueller's investigation into Russian interference in the 2016 election.

Trump has repeatedly condemned the inquiry as a "witch hunt" and seized upon the firing of FBI agent Peter Strzok this week for exchanging anti-Trump texts, saying Mueller's "witch hunt" was built on a "scam" as Strzok had early on been a lead investigator in the case.

"The Rigged Russian Witch Hunt goes on and on as the “originators and founders” of this scam continue to be fired and demoted for their corrupt and illegal activity. All credibility is gone from this terrible Hoax, and much more will be lost as it proceeds. No Collusion!" Trump tweeted Wednesday morning.