Ms. James, in her first public appearance since her federal indictment, said that she and Mr. Mamdani knew what it was like to be threatened and harassed.

The president’s bellicose vow of steep new tariffs, followed quickly by a more conciliatory message, pointed to an internal tug of war over his approach.

Representative Mikie Sherrill, a New Jersey Democrat, said a firm once owned by her Republican opponent, Jack Ciattarelli, spread misinformation about opioids. His campaign has threatened to sue her for defamation.

For many of her fans, she was like a rare bird soaring from bygone days when progress and growing freedoms for women seemed inevitable.

The Trump administration has pushed Republican leaders to redraw House district maps before the midterm elections next year. His party already holds 10 of North Carolina’s 14 congressional seats.

After quietly helping Mel Brooks set the irreverent tone on “Get Smart” and “The Producers,” she had a long collaboration as a writer with the actor and humorist Marshall Efron.