It started with a mystifying missed opportunity on race. It ended with a piercing attack on gender.
Hillary Clinton’s performance in the first presidential debate on Monday veered from uncertain and tentative to firm and, ultimately, scorching.
No amount of practice, it seemed, could fully prepare her — or perhaps anyone — for Donald J. Trump’s hurricane of factual distortion, taunting interruptions and blustery generalities.
Mrs. Clinton seemed to slowly but steadily learn how to confront and subdue Mr. Trump on the fly, as tens of millions of Americans watched.
No moment seemed to better encapsulate her early misfires than an improbable and audacious line of attack from Mr. Trump, who has openly lied about President Obama’s place of birth and brazenly told black Americans that their communities, schools and job opportunities are uniformly awful.
It was Mrs. Clinton, he said, who had grievously offended African-Americans when she described youthful violent criminals in the inner cities as “superpredators.” No matter that the line was 20 years old, or that it was uttered in an entirely different era when America’s cities were ravaged by crime, or that Mrs. Clinton has expressed regret for saying it.
“It’s been horribly met, as you know,” Mr. Trump said. “I think it was a terrible thing to say.”
Yet Mrs. Clinton never answered that damaging claim. Instead, she burrowed deeply into a defense of New York City’s current mayor and his crime-fighting tactics, taking several minutes to circle back to Mr. Trump’s long, flawed relationship with race.
It was a staggering spectacle: Momentarily, perhaps, but against all odds, Mr. Trump — whose business career and candidacy have prompted loud and repeated accusations of racism — had managed to make himself appear as though he were a more faithful advocate for the nation’s black community.
Mrs. Clinton’s challenge was evident from the moment she walked onto the stage at Hofstra University on Long Island: How much respect should she show to a rival of unparalleled incivility, who misrepresents the truth with abandon, crassly rates women’s looks on a scale of 1 to 10 and casually denigrates entire ethnic groups — a man whose words Mrs. Clinton has described as racist, xenophobic and misogynistic?
She signaled, in the opening moments of the debate, that she would take the high road, striding cheerily toward Mr. Trump, shaking his hand and jauntily asking, “How are ya, Donald?”
Mrs. Clinton’s supporters desperately wanted her to savage Mr. Trump, over and over, to bludgeon him with his own fallacious words and messy record in business. She delivered a few of those attacks, aware of something that they were not: that her team of data-mining aides know exactly whom they still need to win over on Nov. 8. And those voters — young people and white, college-educated suburbanites — know full well what Mr. Trump’s inadequacies are.
“I don’t think her job was to disqualify Trump,” said Paul Begala, a longtime Democratic operative who advises a “super PAC” supporting Mrs. Clinton. “Trump has already discredited Trump in their eyes.”
But that calculus may have provided little solace to Mrs. Clinton’s supporters watching on television as she sometimes struggled to repel Mr. Trump’s attack.
Mrs. Clinton eventually found her footing in the second half of the debate. The moderator, Lester Holt, helped.
After Mr. Holt confronted Mr. Trump over his repeated insinuation that Mr. Obama was born outside the United States, he turned to Mrs. Clinton for a response.
“Well,” she said coolly, “just listen to what you heard.”
She deftly tied Mr. Trump’s propagation of a “racist birther lie,” in her words, to what she called his “long record of engaging in racist behavior.” Seeking to establish a decades-long trend, she cited a 1970s housing discrimination lawsuit brought by the Justice Department against the Trump family business.
And by the end, Mrs. Clinton found success with a formula that had bedeviled Mr. Trump at times in Republican primary debates: confronting him over disparaging remarks about the appearance of women.
Mr. Holt again assisted, this time by pressing Mr. Trump on his remark that Mrs. Clinton lacked a presidential “look.” Mr. Trump repeated the charge, but pivoted to attack Mrs. Clinton’s physicality in a different way. He said — repeatedly, and bitingly — that she lacked the “stamina” to serve.
This time, Mrs. Clinton was prepared.
“If he travels to 112 countries and negotiates a peace deal, a cease-fire, a release of dissidents, an opening of new opportunities in nations around the world, or even spends 11 hours testifying in front of a congressional committee,” she began, “he can talk to me about stamina.”
Then she went in for the kill.
Mr. Trump tried to cut short the exchange, sarcastically observing that Mrs. Clinton “has experience, but it’s bad experience.”
But Mrs. Clinton cut in, lobbying for another chance to speak.
“He tried to switch from looks to stamina,” she said. “But this is a man who has called women pigs, slobs and dogs.”
She went on, eagerly, in a way she had failed to when Mr. Trump dredged up her description of young black men as “superpredators.”
Mr. Trump, she said, had called pregnancies an “inconvenience to employers” and had argued that women did not deserve equal pay “unless they do as good a job as men.”
Mrs. Clinton, the first female nominee of a major party, had found her voice defending other women.
She coyly mocked Mr. Trump’s fondness for beauty contests, and contestants — before turning to a particular contestant on her mind.
“He called this woman ‘Miss Piggy.’ Then he called her ‘Miss Housekeeping’ because she was Latina,” she said. “Donald, she has a name.”
Mr. Trump tried to interject, asking incredulously where Mrs. Clinton had found this woman.
“Her name is Alicia Machado, and she has become a U.S. citizen,” Mrs. Clinton said calmly.
“Oh, really?” Mr. Trump shot back.
“And you can bet,” Mrs. Clinton said, “she’s going to vote this November.”
Now it was Mr. Trump who seemed off balance, uncharacteristically caught without an easy comeback.
Mr. Trump was suddenly the one leaving attacks undelivered: He insinuated that he had planned “to say something extremely rough to Hillary, to her family” — most likely an allusion to Bill Clinton’s history of infidelity — before reconsidering.
“I said to myself, I can’t do it,” Mr. Trump said. “I just can’t do it.”