In a potential blow to Crackle, the fledgling Sony Pictures Entertainment streaming service, Jerry Seinfeld’s hit online series “Comedians in Cars Getting Coffee” is on the market.

“Comedians in Cars,” introduced in 2012 on Crackle, features Mr. Seinfeld having free-form conversations with pals like Tina Fey and Jon Stewart. It was nominated for best variety series at the Emmys this year, and Sony has said the show — which has roughly 50 episodes — has generated more than 100 million streams. In the process, it put Crackle on the map.

But Mr. Seinfeld’s contract is expiring, and he has lately felt adrift at Sony, especially since June, when the studio parted ways with Steve Mosko, its television chairman and one of Mr. Seinfeld’s longtime allies, according to multiple people briefed on the matter, who spoke on the condition of anonymity to protect relationships. As a result, the people said, representatives for Mr. Seinfeld have been in talks with the likes of Netflix and Hulu about taking over distribution of “Comedians in Cars.”

In a statement, Sony said, “‘Comedians in Cars’ has been a great part of Crackle’s programming lineup for years, and we look forward to continuing our relationship with Jerry Seinfeld.”