Deadline reports that NBC is canceling Law & Order after 20 seasons, leaving the series tied with Gunsmoke as the longest-running primetime drama.

However, The Futon Critic calls the report "a bit premature," saying that "negotiations are still ongoing and a deal is still possible by Monday," when the network presents its fall lineup.

Cancellation would come as a surprise because, until recently, signs pointed to the network renewing the police procedural/legal drama for a 21st and final season, if only to break Gunsmoke's 35-year-old record. But, according to Deadline's Nellie Andreeva, renewal hinges on "a sizable commitment" from TNT, whose syndication deal expires at the end of the season. Despite its long history with Law & Order, the cable channel is reportedly "skittish" about extending the license after losing $104 million on Without a Trace, a crime drama that performed well for CBS but flopped at TNT.

Law & Order, known for its rigid format, frequently changing cast and signature "" -- chung CHUNG -- debuted in September 1990, becoming the flagship of a lucrative franchise that includes Law & Order: Special Victims Unit, Law & Order: Criminal Intent and the fall-debuting Law & Order: Los Angeles. It's also made the leap across the Atlantic, with adaptations airing in the United Kingdom, France and Russia. The franchise has also had its share of misfires: Crime & Punishment, Law & Order: Trial by Jury and Conviction.