She rarely ad-libbed and did not interrupt. She sprang no surprise attacks and let Mr. Trump off the hook several times as he plainly struggled.
Instead, Mrs. Clinton coolly prosecuted the case against Mr. Trump that she has offered all along, calling him unfit for the presidency and describing his candidacy as built on hate. “He owes our country an apology,” Mrs. Clinton said.
She did not create an electric moment in the debate — the kind that might dominate news coverage for days — and with Mr. Trump’s fortunes falling, she likely did not need to. In a rare off-the-cuff remark, she said Mr. Trump’s campaign was “exploding,” an assessment few Republicans would dispute.