MADISON, Wis. (AP) — David Crowley’s razor-thin primary win over a democratic socialist in swing state Wisconsin sets up a match against a congressman who has voted with President Donald Trump 100% of the time, a dream scenario for Democrats and a potential nightmare for Republicans.

Crowley overcame Francesca Hong in dramatic, narrow fashion in Tuesday’s primary, stunning pundits and pollsters who had long placed Hong as the front-runner. That means Republican U.S. Rep. Tom Tiffany must pivot to face a challenger from Milwaukee, the state’s largest source of Democratic voters, known for working across the aisle with Republicans.