Five years ago progressive Democrats seemed to be on the rise. Alexandria Ocasio-Cortez had just ousted a moderate Democrat, and Senator Bernie Sanders looked like he could win the party's nomination.

Galvanized by President Donald Trump’s sweeping second-term agenda, a new generation of progressive Democrats is working to redefine the party's future. The original "Squad," a group of young, ...

Ms. Ainsley, an adviser to Keir Starmer before he became prime minister of Britain, is the director of the Project on Center-Left Renewal at the Progressive Policy Institute. See more of our coverage ...