Progressive challenger Cori Bush beats Rep. Lacy Clay in primary

Liberal challenger Cori Bush defeated Rep. Lacy Clay (D-Mo.) in a primary for Clay's St. Louis-based House seat on Tuesday - a seismic loss for the Congressional Black Caucus, which has tried to snuff out challenges from younger candidates.

Bush's victory came two years after her first challenge to Clay, which the incumbent won by 20 percentage points. The Black Caucus had successfully defended two other incumbents from progressive opponents earlier this year.

But Bush, who participated in the 2014 protests in Ferguson, Mo., after the police shooting of an unarmed black man, made her activism the centerpiece of her 2020 campaign. She worked for Sen. Bernie Sanders' 2020 presidential bid, and Sanders endorsed and publicly boosted her in the run-up to Tuesday's primary.