The fight for Michigan’s open Senate seat is becoming an early proxy war over the Democratic Party’s future, with progressives and establishment leaders lining up behind rival candidates in one of the country’s most important battleground states.

The contest to replace retiring Sen. Gary Peters (D-MI) has crystallized into a three-way Democratic primary, though much of the attention has centered on Rep. Haley Stevens (D-MI) and former public health director Abdul el Sayed. State Sen. Mallory McMorrow (D-MI) is also seeking the nomination, positioning herself as an alternative who can appeal across the party’s ideological divide.