Kamala Harris has put Donald Trump on the defensive in a combative US presidential debate with a stream of attacks on abortion limits, his fitness for office and his myriad legal woes.

Former prosecutor Harris, 59, appeared to get under Trump’s skin more than once.

Her sharp attacks prompted a visibly angry former president to deliver a stream of falsehood-filled retorts as both candidates sought a campaign-altering moment in the closely fought US election campaign.

The Harris campaign was so pleased with her tactics that an adviser described the result to CNN afterwards as “an embarrassment of riches”. They included Harris goading Trump by saying people often left his campaign rallies early “out of exhaustion and boredom”.

“My rallies, we have the biggest rallies, the most incredible rallies in the history of politics,” a visibly rattled Trump – who has been frustrated by the size of Harris’s crowds – snapped back.

He then pivoted to a debunked conspiracy theory claiming that Haitian immigrants in Springfield, Ohio, are eating pets.

“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. And this is what’s happening in our country, and it’s a shame,” Trump said.

With mics muted unless candidates were speaking, Harris was limited to facial expressions to react to some of Trump’s wilder claims. The pet-eating story drew an expression of disbelief and then a chuckle.

“Talk about extreme,” Harris said.

She also criticised Trump over his criminal conviction for covering up hush money payments to a porn star as well as his other indictments and a civil judgment finding him liable for sexual assault. Trump has denied wrongdoing and again accused Harris and the Democrats of orchestrating all of the cases without evidence.

Trump also repeated his false claim that his 2020 election defeat was due to fraud, called Harris a “Marxist” and asserted falsely that migrants have caused a violent crime spree.

With eight weeks before the November 5 election, and days until early voting starts in some states, the debate – the only one scheduled – presented opportunities and risks for each candidate in front of a televised audience of tens of millions of voters.

The candidates opened the debate by focusing on the economy, an issue that polls show favours Trump.

Harris attacked Trump’s intention to impose high tariffs on foreign goods – a proposal she has likened to a sales tax on the middle class – while touting her plan to offer tax benefits to families and small businesses.

“Donald Trump left us the worst unemployment since the Great Depression,” Harris said, referring to his years as Republican president from 2017 to 2021.

Unemployment peaked at 14.8 per cent in April 2020 and at 6.4 per cent when Trump left office. It was far higher in the Great Depression.

Trump criticised Harris for the persistent inflation during the Biden administration’s term, though he overstated the level of price increases.

Inflation, he said, had “been a disaster for people, for the middle class, for every class”.

Harris delivered a lengthy attack on abortion limits, speaking passionately about women denied emergency care and victims of incest unable to terminate their pregnancies due to statewide bans that have proliferated since the US Supreme Court eliminated a nationwide right in 2022.

Three Trump appointees were in the majority of that ruling.

She also claimed Trump would support a national ban, an assertion Trump called a lie.

Trump, who has sometimes struggled with messaging on abortion, claimed falsely that Harris and Democrats support infanticide – or, as he put it, “executing babies”. Moderator Linsey Davis quickly noted that infanticide is illegal in every US state.

“As I said, you’re going to hear a bunch of lies,” Harris said.

Harris also sought to tie Trump to Project 2025, the conservative policy blueprint that proposes expanding executive power, eliminating environmental regulations and making it illegal to ship abortion pills across state lines, among other right-wing goals.

Trump retorted that he had “nothing to do” with Project 2025, though some of his advisers were involved in its creation.

The candidates also exchanged barbs over the Israel-Gaza war and the Russian invasion of Ukraine, though neither offered specifics on how they would seek to end each conflict.

-with AAP