Kamala Harris came out on top after the Democratic presidential nominee faced off against the Republicans' Donald Trump in what could be their only debate before the November election, according to a snap poll.
United States broadcaster CNN polled 605 registered voters who watched on Tuesday. Some 63 per cent viewed vice-president Harris as the top performer, while 37 per cent thought former US president Trump was the standout.
CNN says the poll only reflects the opinions of those who tuned in and not the full voting public. It says the poll had a margin of error of plus or minus 5.3 percentage points.
Following the debate on Wednesday (AEST), US pollster Nate Silver wrote there was a "strong consensus that Harris won the night".
"Bitcoin prices are down, which also implies a loss for Trump," Silver wrote.
"Even the Fox News panel that I caught at the tail end of the evening seemed to concede that it was a win for Harris."
In a sign of confidence in the debate's outcome, challenged Trump to a second round in October.
Trump afterwards took the rare step of going into the nearby "spin room," a job usually left to supporters, where he told reporters: "This was my best debate."
Asked about the Harris campaign seeking a second debate, Trump told Fox News: "She wants it because she lost."
"I have to think about it, but if you won the debate, I sort of think maybe I shouldn't do it. Why should I do another debate?" he said.
Presidential debates do not necessarily change voters' minds, but they can be deeply consequential. US President Joe Biden's poor performance against Trump in June led him to .
Opinion polls currently show a tight race, and the 5 November contest could come down to tens of thousands of votes in a handful of states. Even a small shift in public opinion could alter the outcome.
The two candidates are effectively tied in the seven battleground states likely to decide the election, according to polling averages compiled by the New York Times.
Here are some key takeaways from the debate:
Riling her rival
Harris made a point to get under Trump's skin, as her campaign had forecast — and it appeared to work.
She urged viewers to attend a Trump rally, where she said Trump would say bizarre things such as windmills cause cancer (something he has, in fact, said) and where, she taunted, attendees would leave out of exhaustion and boredom (something they have, in fact, done).
Trump, who prides himself on the crowds he draws, was clearly riled.
"My rallies, we have the biggest rallies, the most incredible rallies in the history of politics," he said. He accused Harris of busing in attendees to her rallies.
Donald Trump's running mate JD Vance (centre). Source: AAP, EPA / Jim Lo Scalzo
"In Springfield, they're eating the dogs! The people that came in, they're eating the cats!" Trump said. "They're eating the pets of the people that live there."
City officials in Springfield have said those reports are untrue, which the ABC moderators pointed out after Trump’s comments.
"Talk about extreme," Harris responded, laughing.
'Weaponised' justice
Trump and Harris accused each other of conspiring to "weaponise" the Justice Department in a bid to go after their enemies.
Trump said the indictments he faces for conspiring to overturn his 2020 election loss and for his — as well as his conviction for forging documents related to hush money payments to a porn star — are all the result of a conspiracy cooked up by Harris and Biden. There is no evidence for that assertion.
Donald Trump and Kamala Harris accused each other of conspiring to "weaponise" the Justice Department in a bid to go after their enemies. Source: Getty, AFP / Saul Loeb
"Understand this is someone who has openly said he would terminate, I'm quoting, terminate the Constitution," she said.
The heated exchange underlined how Harris and Trump see the stakes of this election as existential. Both claimed their opponent to be a threat to democracy itself.
A handshake
Heading into the debate, there was a question as to how Harris and Trump, who have never met, would greet each other.
Harris settled the issue, definitively. She walked over to Trump at his podium, extended her hand, and introduced herself as "Kamala Harris".
It was an assertive way to approach a man who has spent weeks insulting her with racist and sexist attacks. Trump had no choice but to accept the gesture.
Kamala Harris walked over to Donald Trump's podium to shake his hand. Source: AAP, AP / Alex Brandon
A schism on abortion
The two candidates also engaged in a fractious debate about abortion, an issue where polls show Harris has the upper hand.
Trump defended the US Supreme Court's 2022 ruling and sent the issue back to individual states, arguing, incorrectly, that it was an outcome desired by both Republicans and Democrats. Democrats have long supported a constitutional right to abortion.
"I did a great service in doing it. It took courage to do it," Trump said.
Trump contended that some states allow babies to be aborted after birth, a point corrected by ABC News moderator Linsey Davis.
Donald Trump says he will "think about" a second debate with Kamala Harris. Source: AAP, SIPA USA / Bastiaan Slabbers
"This is what people wanted?” Harris asked. "People being denied care in an emergency room because healthcare providers are being afraid of being hauled off to jail?"
Trump was asked whether he would veto a federal abortion ban if one were passed by Congress. He insisted a federal ban would never happen.
Worlds apart
One of the most heated policy discussions came when Trump and Harris clashed over how they would handle .
The candidates' responses revealed the degree to which their views on America's role in the world fundamentally differ.
Trump refused to say he wanted Ukraine to win the war, even as ABC moderator David Muir pushed him on the point, saying only that he wanted to wrap up the conflict as soon as possible.
Harris shot back, arguing that what Trump really wanted was Ukraine's quick and unconditional capitulation.
"If Donald Trump were president, [Russian President Vladimir] Putin would be sitting in Kyiv right now," Harris said.
She also pushed back at Trump's claim she had been sent by Biden to talk to Putin to resolve the conflict. Harris has never met with Putin but has met several times with Ukrainian President Volodymyr Zelenskyy.
"I said at the beginning of this debate, you're going to hear a bunch of lies coming from this fellow, and that is another one."
