Potential Republican presidential candidate Fred Thompson is not expected back for ”Law & Order’s” upcoming eighteenth season.

NBC Entertainment President Kevin Reilly claimed no insider knowledge of Thompson’s political plans, but his statement indicated the seriousness of Thompson’s presidential musings. The former Tennessee senator has been making speaking appearances and blogging on issues in recent weeks as he considers a candidacy.

”It’s pretty clear that Fred is going to be leaving the cast of the show no matter what,” Reilly said at a news conference on NBC’s fall schedule.

He later left the door slightly ajar by saying it was ”highly unlikely” Fred would be back. Thompson certainly wouldn’t return to prime-time network television if he chooses to run, he said.

Fred plays the district attorney Arthur Branch during L&O’s ripped-from-the-headlines New York-set criminal-justice show.