The surprise decision Tuesday again complicates for Democrats in Michigan, who will be forced to defend an open seat in the battleground state for the second straight election cycle. Peters led the Democrats’ Senate campaign efforts from 2021 to 2025 and helped the party hold control of the chamber in 2022 before Republicans flipped it last year.

Gary Peters of Michigan said he’ll retire at the end of his term and forgo a 2026 re-election campaign. The decision creates a competitive open-seat contest in one of the nation’s most competitive battleground states.