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.

Democratic U.S. Sen. Gary Peters, of Michigan, announced Tuesday that he will not run for a third six-year term in 2026 leaving an open Senate seat.

His unexpected retirement in the battleground states comes in an already difficult Senate cycle for Democrats.