In St. Louis, Testing Liberal Might Against a Democratic Fixture

The contest has grown exceedingly bitter, and Mr. Clay, 64, has come to view it not only as a fight for his own survival, but a chance to snuff out an upstart movement he sees as dangerously divisive. In an interview last week, the congressman suggested that the effort to unseat him by Ms. Bush, who is also Black, rests on a racist premise.

“The easy, racist way to lay it out is, ‘Look at Clay — what has he done for his district?’” he said, adding, “I fight for that district every single day.”

Mr. Clay accused the groups like Justice Democrats and Brand New Congress that have helped groom progressive primary challengers of targeting members of the Congressional Black Caucus specifically because “they think we are easy targets.”

“She’s a prop,” Mr. Clay said of Ms. Bush. “They use her to raise money to support their infrastructure.”

Mr. Clay has a powerful infrastructure of his own.

A Clay has represented part of St. Louis in Congress since 1969. William Lacy Clay Sr. was an icon of the civil rights movement in the city and a founding member of the Congressional Black Caucus. When he retired nearly two decades ago, his son, William Lacy Clay Jr., inherited the seat and the loyalty of Black St. Louisans who have sent him back to Washington every two years since.

By some estimates, a majority of voters in the city have never voted for a congressman by any other name. Because Democrats so dominate this district, the real contest is fought each term in the Democratic primary, not the general election.

Mr. Clay is not bashful about his seniority in the Black Caucus and among the intensely hierarchical House Democratic Caucus, arguing that his easy access to the levers of power helps his district. He has the backing of Speaker Nancy Pelosi and many of the party’s establishment pillars, like the Planned Parenthood Action Fund.