For a moment there, Nancy Pelosi looked lost. After Rep. Alexandria Ocasio-Cortez (D., N.Y.) accused her of “singling out . . . newly elected women of color” for criticism, it fell to Donald Trump to defend the speaker of the House. To call Mrs. Pelosi a racist, Mr. Trump told reporters on Friday, “is a disgrace.”

Not exactly the rescue she was hoping for. Fortunately for her, by Sunday Mr. Trump had followed up with a series of tweets saying the progressive Democratic congresswomen accusing Mrs. Pelosi of racism should...