Ron Johnson on Missing Texts, Secret Meetings: We're Going to Start Investigating the FBI

Attorney Alan Dershowitz said Wednesday he's concerned that Special Counsel Robert Mueller will choose to go after President Trump on a charge of obstruction of justice.

"A great worry is that because [Mueller] doesn't have anything really substantial, he may go after obstruction of justice, which would create a constitutional crisis," he said.

Dershowitz, a Harvard Law professor emeritus and lifelong Democrat, responded on "America's Newsroom" to a new report of Mueller interviewing Trump cabinet members, including Attorney General Jeff Sessions.

Mueller is also reportedly moving closer to interviewing Trump on the departure of former National Security Adviser Michael Flynn and the firing of FBI Director James Comey.

"Firing Comey, telling Comey not to investigate Flynn, those are all within the president's constitutional authority. The other place it may be going is toward collusion, but collusion is not a crime," Dershowitz said, adding he has not yet seen evidence of "crimes being committed near the Oval Office."

He said he's concerned that Mueller will end his probe with a "whimper," going after "low-hanging fruit" on matters "not directly related to the thrust of the investigation."

Dershowitz said Trump has no choice but to talk to Mueller, since the former FBI director could issue him a subpoena if he refuses. He also said he sees no reason for Mueller to be removed because "he is not a partisan."

But Dershowitz acknowledged that allegations of abuses within the FBI must be examined.

"Every civil libertarian, whether a liberal or conservative, should be concerned about abuses from within the FBI," he said.

Watch his analysis above.

Dershowitz: Mueller Probe Is 'Worst Possible Way' to Look Into Russian Interference

Tomi Lahren: If Media Covered Missing FBI Texts, It Would 'Invalidate' Their Trump-Russia Narrative