Michigan Democrats sought Wednesday to turn the page on a bitter Senate primary, as Republicans made their opening attacks on newly anointed Democratic nominee Abdul El-Sayed.

El-Sayed, a former local public health official running on an unabashedly progressive agenda, narrowly defeated the more centrist Rep. Haley Stevens in a divisive primary for the open Senate seat in battleground Michigan. He is now set to face Republican former Rep. Mike Rogers in what will be a major test for Democrats’ left flank as it seeks to prove that a progressive message can carry candidates over the finish line outside of deep-blue territory.

The stakes in November are high. Senate Democrats see a path to winning control of the chamber, but holding the Michigan seat would be crucial to that effort.

Republican groups responded to El-Sayed’s win by quickly trying to cast him as too extreme for Michigan. The state has swung back and forth between the parties in recent presidential elections but hasn’t elected a Republican to the Senate in more than 30 years.

President Donald Trump on social media referred to El-Sayed’s win as “Great News for the Republican Party” while branding the Democratic nominee a “Communist loser who hates Jews and Israel.”