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.

Tuesday’s Michigan Senate primary between Haley Stevens and Abdul El-Sayed has become a bitter referendum on many of the fights Democrats are having nationally.

Michigan voters will decide a competitive Democratic U.S. Senate primary Tuesday in a contest that will have major implications for control of the chamber next year.