WASHINGTON — Sen. Ben Cardin, D-Md., announced Monday that he has decided not to seek re-election next year.

"It's time," Cardin said in an interview with his local newspaper, The Baltimore Sun, which first reported the news.

"I always knew this election cycle would be the one I would be thinking about not running again, so it's not something that hit me by surprise. I enjoy life. There are other things I can do," he said.

Cardin, 79, also said in a statement Monday that while he won't be on the ballot in 2024, there's a lot of work to be done over the next two years.

"During the next two years, I will continue to travel around the state, listening to Marylanders and responding to their needs," he said. "My top priorities include continuing our progress for the Chesapeake Bay, helping the people of Baltimore City deal with the challenges they face, and permanently expanding opportunities for telehealth, mental and behavioral health."

His departure leaves a coveted vacancy open for possible Senate contenders, from Democratic Rep. Jamie Raskin to GOP former Gov. Larry Hogan, among others.

Cardin's retirement could lead to a crowded primary in the heavily Democratic state during the presidential election cycle. Ten Democrats ran for governor last year — including eventual primary and general election winner Wes Moore, as well as former Labor Secretary Tom Perez, former state Comptroller Peter Franchot and former Prince George's County Executive Rushern Baker.

Cardin's office did not immediately respond to a request for additional comment.

Cardin hasn't ruled out doing other things professionally, telling the Sun: "I actually think I'd be a good professor, a teacher. I might do some of that. ... I think I'm at that top of my game physically, I really do. But I'm not skiing and I'm not climbing steep cliffs anymore and, as I go down steps, I'm holding on. So things are changing."

Democrats, who narrowly hold the Senate majority, face a competitive race for control of the Senate next year. They will have to defend 20 seats, not including those of three independents, two of whom have caucused with the party. That's compared to only 10 Republicans who are up for re-election.

Other Democrats who are up for re-election who have also announced plans to retire from Congress include Sens. Dianne Feinstein of California and Debbie Stabenow of Michigan.

Cardin has served in Congress for more than three decades. He was a member in the House from 1987 to 2007 and has been in the Senate since then. He chairs the Small Business and Entrepreneurship Committee and has also been its ranking member and the ranking member of the Foreign Relations Committee.

This article was originally published on NBCNews.com