State Representative Angie Nixon, a progressive firebrand, marshaled grass-roots enthusiasm to defeat a moderate who dramatically out-raised her. Can it carry her to victory in November?

© Saul Martinez for The New York Times

Scott Singer will face the winner of the Democratic primary in one of the most competitive House races in the nation.

© TNS/ABACA, via Reuters

The congresswoman won her party’s nomination in Florida’s 20th District over several Black candidates who sharply criticized her decision to run there.

© Eric Lee for The New York Times