Abdul El-Sayed is trying to swing the Midwest to the left, while Haley Stevens runs with air cover from outside groups and an endorsement from Gov. Gretchen Whitmer.

The influential voting bloc could be key to whether Democrats can retain a Senate seat in the fall.

The stark choice facing Michigan’s Democratic voters in the August 4 Senate primary was on display Monday night, as the two candidates closed their final debate by pitching…