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.

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

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.