Sen. Gary Peters of Michigan, who spearheaded the Democratic campaign in the Senate for the previous two election cycles, has declared that he will not run for a third term in 2026, opening up a fiercely contested battleground seat that both major political parties are likely to pursue.

The 66-year-old’s shocking decision on Tuesday to resign after only two terms is unexpected and presents a challenge for Michigan Democrats at a time of upheaval, as they will probably have to split their strong bench between the 2026 Senate and gubernatorial contests.

“I always thought there would be a time that I would step aside and pass the reins for the next generation. I also never saw service in Congress as something you do your whole life,” Peters told The Detroit News in an interview published Tuesday.

“And that goes back to 2008 when I first won that House seat. I thought it would be for a matter of a few terms that I would serve, and then I would go back to private life. I want to be very clear: I’m not retiring. I’m just not running for reelection in the Senate. I hope, God willing, I have a lot more good years ahead,” Peters added.