Michigan’s Senate primary is rapidly becoming the next major battleground in the Democratic Party’s escalating fight between establishment leaders and insurgent progressives, as Democrats increasingly view the race as a test of whether the party’s antiestablishment wave can expand beyond deep-blue enclaves.

After state Sen. Mallory McMorrow exited the race amid fundraising and polling struggles, progressives quickly consolidated behind Bernie Sanders-backed candidate Abdul El Sayed, while establishment Democrats rallied around Rep. Haley Stevens, who is backed by Senate Minority Leader Chuck Schumer (D-NY) and EMILYs List.