"I will be introducing an amendment next week to block the President from punishing and intimidating his critics by arbitrarily revoking security clearances. Stay tuned," Warner said in a Twitter post on Friday.
The White House is also reviewing the security clearances of other Obama administration officials including former FBI Director James Comey and former Director of National Intelligence James Clapper.
Brennan in a recent New York Times piece accused Trump of colluding with Russia vis-a-vis the 2016 election — a charge the president and the Kremlin have repeatedly denied.
On Friday, Senator Rand Paul in an interview said Brennan deserved to have his clearance revoked for leaking classified intelligence information.