Phones rise across the room as Chris Rabb steps to the front. It is the second day of the national summit for the Democratic Socialists of America (DSA) in Chicago, and Rabb is fresh off an upset that launched the movement’s summer winning streak, defeating party-backed rivals in a Democratic congressional primary outside Philadelphia. Subscribe to TIME’s YouTube channel ►► ti.me/subscribe-time Subscribe to TIME: ti.me/3E3UCqt Get the day’s top headlines to your inbox, curated by TIME editors: ti.me/48dFNwQ Follow us: X (Twitter): ti.me/3xTVwSk Facebook: ti.me/3xWI2Fg Instagram: ti.me/3dO9Rcc #DSA