Votes are being counted in Michigan, where Democratic voters are settling a Senate primary that has become the year’s most significant test of how the party’s electorate is weighing questions of ideology and electability.

Progressive former public health official Abdul El-Sayed faces the more moderate Rep. Haley Stevens in the race to take on Republican former Rep. Mike Rogers in November. Holding onto the seat, now held by retiring Sen. Gary Peters, is crucial to Democrats’ chances of the net four-seat gain they need in this year’s midterm elections to win a Senate majority.

The race was tight, with many votes left to count, as of early Wednesday morning.

It was the most closely watched race — and one of multiple progressive vs. moderate contests — on Tuesday’s slate of primaries in Kansas, Michigan, Missouri, Virginia and Washington state

Voters set the matchups in the governor’s races in Michigan and Kansas. They also chose their nominees in key congressional races in Virginia. And an incumbent Democrat held off a democratic socialist former congresswoman vying to win back her old seat in Missouri.