LANSING, Mich. (AP) — Michigan Sen. Gary Peters, who led the Democrats’ Senate campaign efforts the past two election cycles, has announced he will not seek a third term in 2026, creating a highly contested battleground seat expected to be coveted by both major political parties.

The 66-year-old’s unexpected decision Tuesday to step aside after just two terms comes as a surprise and poses a challenge for Democrats in Michigan during a turbulent period, likely dividing their strong bench between the gubernatorial and Senate races in 2026.

“After three terms in the House and two terms in the Senate, I believe now is time for me to write a few more paragraphs in my current chapter and then turn over the reins," Peters said in a YouTube video. “I will therefore not seek reelection in 2026.”

Having lost Michigan in the presidential race, Peters’ decision forces Democrats to defend a critical Senate seat in Michigan without the advantage of an incumbent, complicating their efforts to regain control of the chamber, where Republicans hold a 53-47 majority. Expected to be among the names most circulated for the position is Pete Buttigieg, the former U.S. transportation secretary, who moved to Michigan in recent years.

This is the second consecutive cycle in which Democrats must navigate the challenge of defending an open Senate seat in Michigan, a state won by Republican Donald Trump in the presidential contest in 2024.

Longtime Sen. Debbie Stabenow shocked many observers by announcing she would not seek a fifth term in 2024. Democratic Sen. Elissa Slotkin held that seat for the party by a narrow margin.

First elected to the Senate in 2014 after serving three terms in the U.S. House, Peters has earned a reputation as a mild-mannered and moderate politician. Besides leading the Senate Democrats’ campaign efforts from 2021 until earlier this year, he also chaired the Senate Homeland Security Committee from 2021 to 2025 and is currently the ranking member on the committee.

Peters earned praise from many Democrats for aiding the party’s strong performance in the 2022 midterms by winning a number of hotly contested races to hold control of the Senate. But two years later, Republicans flipped several highly competitive seats, costing Democrats their majority in the upper chamber.

Peters' decision sets up a major midterm election in the state. Second term Democratic Gov. Gretchen Whitmer is term-limited, and the field for her successor is already taking shape.

Detroit Mayor Mike Duggan announced after the 2024 election that he is running for governor as an independent. Democratic Secretary of State Jocelyn Benson and Republican leader of the state Senate Aric Nesbitt have launched campaigns as well.

Buttigieg, who has been weighing a run for governor, is also considering running for the Senate in Michigan. Buttigieg, a former mayor of South Bend, Indiana, moved to Michigan shortly after his unsuccessful campaign for president in 2020.

The news of the open Senate seat quickly drew interest from many public officials eying higher office. State Sen. Mallory McMorrow, a Democrat whose profile has risen thanks to a viral floor speech she gave in 2022, and second term Lt. Gov. Garlin Gilchrist II are potential candidates.

Whitmer, a potential 2028 presidential candidate, said she is not interested in pursuing the open Senate seat while speaking on ABC's “The View” on Tuesday.

“I’ve got two more years on my term. I’ve got a lot of things I want to get done as governor," she said. “What comes after that, I don’t know yet.”

The Detroit News first reported Peters’ decision.