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.