AMNA NAWAZ: Welcome to the "News Hour."

Tens of millions of Americans tuned into last night's consequential presidential debate between Vice President Kamala Harris and former President Donald Trump.

GEOFF BENNETT: The contentious debate may be the only face off of the campaign season.

Vice President Harris tried to walk a fine line between being both an incumbent and a change candidate all while fending off attacks from Donald Trump.

And the former president was repeatedly fact-checked for inaccuracies.

Laura Barron-Lopez reports.

KAMALA HARRIS, Vice President of the United States (D) and U.S. Presidential Candidate: Kamala Harris.

DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: Nice to see you.

Have fun.

LAURA BARRON-LOPEZ: The night began cordially before the gloves came off.

KAMALA HARRIS: World leaders are laughing at Donald Trump.

I have talked with military leaders, some of whom worked with you, and they say you're a disgrace.

DONALD TRUMP: She got zero votes, and when she ran, she was the first one to leave because she failed.

LAURA BARRON-LOPEZ: It was their first face-to-face meeting, and their first head-to-head clash on the issues, like on the economy.

KAMALA HARRIS: I have a plan, $6,000 for young families for the first year of your child's life to help you in that most critical stage of your child's development.

I have a plan.

DONALD TRUMP: She copied Biden's plan, and it's like four sentences, like run, Spot, run.

Four sentences that are just, oh, we will try and lower taxes.

LAURA BARRON-LOPEZ: The former president tried to link Harris to President Biden.

DONALD TRUMP: She is Biden.

She's trying to get away from Biden.

I don't know the gentleman she says.

She is Biden.

KAMALA HARRIS: Clearly, I am not Joe Biden, and I am certainly not Donald Trump.

LAURA BARRON-LOPEZ: And Harris, a former prosecutor, repeatedly baited Trump.

KAMALA HARRIS: They're so clear they can manipulate you with flattery and favors.

LAURA BARRON-LOPEZ: From highlighting his fondness of dictators to needling Trump about the crowd size at his rallies.

KAMALA HARRIS: I'm going to invite you to attend one of Donald Trump's rallies, because it's a really interesting thing to watch.

You will see during the course of his rallies, he talks about fictional characters like Hannibal Lecter.

He will talk about windmills cause cancer.

And what you will also notice is that people start leaving his rallies early out of exhaustion and boredom.

DONALD TRUMP: People don't leave my rallies.

We have the biggest rallies, the most incredible rallies in the history of politics.

That's because people want to take their country back.

LAURA BARRON-LOPEZ: For much of the night, Trump was on defense, not answering whether he'd sign or veto a national abortion ban.

LINSEY DAVIS, ABC News Live "Prime" Anchor: If I could just get a yes or no, because you're running mate, J.D.

Vance, has said that you would veto if you did come to your desk.

DONALD TRUMP: Well, I didn't discuss it with J.D., in all fairness.

Look, we don't have to discuss it.

LAURA BARRON-LOPEZ: Refusing to say if he thought defending Ukraine against Russia was in America's national security interests.

DAVID MUIR, "World News Tonight" Anchor and Managing Editor: I want to ask you a very simple question tonight.

Do you want Ukraine to win this war?

DONALD TRUMP (R) FORMER PRESIDENT OF THE UNITED STATES AND PRESIDENTIAL NOMINEE: I want the war to stop.

I want to save lives that are being uselessly -- people being killed by the millions.

It's the millions.

DAVID MUIR: Just to clarify in the question, do you believe it's in the U.S. best interests for Ukraine to win this war, yes or no?

DONALD TRUMP: I think it's the U.S. best interests to get this war finished and just get it done.

LAURA BARRON-LOPEZ: And taking no responsibility for his role in the January 6 attack on the Capitol.

DAVID MUIR: Is there anything you regret about what you did on that day, yes or no?

DONALD TRUMP: I had nothing to do with that, other than they asked me to make a speech.

LAURA BARRON-LOPEZ: Vice President Harris used that moment to appeal to undecided voters.

KAMALA HARRIS: It's time to turn the page.

And if that was a bridge too far for you, well, there is a place in our campaign for you to stand for country, to stand for our democracy, to stand for rule of law, and to end the chaos.

LAURA BARRON-LOPEZ: Moments after the debate ended, Harris picked up a superstar endorsement, Taylor Swift.

And in a rare move for a presidential candidate, Trump went to the spin room afterward.

Over the last 24 hours, in multiple FOX News interviews, Trump questioned whether he'd do another debate, and said ABC should lose its license.

DONALD TRUMP: It was three to one.

It was a rigged deal, as I assumed it would be.

I think ABC took a big hit last night.

I mean, to be honest, they're a news organization.

They have to be licensed to do it.

They ought to take away their license for the way they did that.

LAURA BARRON-LOPEZ: Trump and Republicans were quick to attack the moderators for fact-checking him in real time, including on abortion.

DONALD TRUMP: Her vice presidential pick says abortion in the ninth month is absolutely fine.

He also says execution after birth.

It's execution, no longer abortion, because the baby is born.

LINSEY DAVIS: There is no state in this country where it is legal to kill a baby after it's born.

LAURA BARRON-LOPEZ: And on a debunked conspiracy theory about Haitian immigrants in an Ohio town eating pets, one that's been peddled by far right activist and 9/11 truther Laura Loomer, who traveled with Trump to the debate.

DONALD TRUMP: In Springfield, they're eating the dogs, the people that came in.

They're eating the cats.

They're eating -- they're eating the pets of the people that live there.

DAVID MUIR: ABC News did reach out to the city manager there.

He told us there had been no credible reports of specific claims of pets being harmed, injured or abused by individuals within the immigrant community.

DONALD TRUMP: Well, I have seen people on television.

DAVID MUIR: Let me just say... LAURA BARRON-LOPEZ: Katie Sanders of PolitiFact defended the moderators.

KATIE SANDERS, Editor in Chief, PolitiFact: When a candidate is lobbying conspiracy theories, that's kind of a softball for a moderator, and it's particularly glaring if you don't address that.

LAURA BARRON-LOPEZ: She said Harris was not immune from critique for leaving out finer details, but it was Trump who required more immediate fact-checking.

KATIE SANDERS: I think one candidate, former President Trump, was repeating conspiracy theories that are pretty well-known to be false at this point and so it's almost easier to call those out in real time.

LAURA BARRON-LOPEZ: At Ground Zero today, disagreements were put aside.

President Biden and Vice President Harris stood just feet away from former President Trump and running mate J.D.

Vance as the nation remembered the nearly 3,000 lives lost on this day 23 years ago, the former president and Vice President Harris even shaking hands at the remembrance.

But, tomorrow, the race is back on with less than eight weeks to go before Election Day.