FRED Thompson’s failed presidential bid could win him a guest-starring spot on “Law & Order.”

It’s no sure thing, and show insiders aren’t commenting, but Thompson has inked a new deal with the powerhouse William Morris Agency to find him TV and movie work.

One landing spot could be back on NBC’s “L&O,” on which Thompson played gruff DA Arthur Branch for five years.

Thompson wouldn’t be a regular again, though; his spot was taken by show vet Sam Waterston, whose Jack McCoy was “promoted” to DA when Branch left (ostensibly to return to his private law practice).

Thompson joined “L&O” in 2002 and asked to be let out of his contract in May 2007, when he was contemplating a White House bid but hadn’t yet announced his candidacy (he did that last Sept. 5 on “The Tonight Show”).

“L&O” began its 18th season last January and is expected to return next fall.

“It’s premature to speculate,” a show spokeswoman said yesterday.