Michigan Democrats on Tuesday will settle a Senate primary that has emerged as the most significant test of the party’s direction this year — one that will gauge whether the progressive insurgency that has toppled establishment figures and incumbents on deep blue turf all spring and summer extends into one of the nation’s biggest political battlegrounds.

Progressive former public health official Abdul El-Sayed faces the more moderate Rep. Haley Stevens in the race to take on Republican former Rep. Mike Rogers. The race has implications that extend into 2028, offering prospective presidential candidates a glimpse at what the party’s electorate wants in Michigan, likely to be one of the first six states to vote in the Democratic nominating calendar and a must-win in the general election.

Most important, though, is what Tuesday’s outcome means for Democrats’ chances of netting the four-seat gain they need to take the Senate majority in November. The Democratic establishment in Washington believes Stevens is best-positioned to keep the seat of retiring Sen. Gary Peters in the party’s hands. But if El-Sayed wins, progressives who have long maintained that their approach can build a new coalition will have their chance to prove it.