it's possible that the president could try to use what's known as executive authority, that is intended to keep some of the deliberations inside the white house protected. it's unclear right now you if the president will do that. it's a long shot. it's a challenge. but he does have a certain amount of power that could cope comey quiet. >> president trump and james comey, the fbi director he fired, could be headed for a new power struggle this week. comey is set to go public thursday, about the russia investigation. but the white house is not ruling out a move that could block comey from testifying on capitol hill. by claiming an executive branch privilege that protects the privacy of a president's conversations with senior officials. in a new letter, democratic lawmakers warn the white house any assertion of privilege by the president would be seen as an effort to obstruct the truth. >> that preemptive strike came after white house officials,