Virginia Sen. Mark Warner, the top Democrat on the Intelligence Committee, blasted President Trump's decision to revoke former CIA Director John Brennan's security clearance.

Warner said the move was "Nixonian" and invokes "an eerie memory of an enemies list," and wondered aloud whether Trump would pursue action against Special Counsel Robert Mueller next.

Warner, whose committee is probing whether Trump colluded with Russians to steal the 2016 election, said the president is trying to distract from internal White House troubles -- including Congress' investigation.

He said Trump is trying to deflect attention from former campaign chairman Paul Manafort's 2005 tax fraud case playing out across the Potomac in an Alexandria, Va. courtroom -- as well as from "some of the issues with his former staffer, Omarosa [Manigault Newman]."

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"The White House feels under siege," Warner said, adding that revoking Brennan's clearance precludes the former official's ability to "speak truth to power" about Trump's shortcomings.

Brennan has come under fire for several tweets and television appearances condemning the president.

Critics of Brennan have responded by noting his vocal partisanship and the fact he supported the Communist Party's presidential candidate in the 1970s in the midst of the Cold War.

"What we've seen today is one more traditional norm being struck down by this president," Warner said, speaking to a gaggle of press in a Senate office building.

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