Philadelphia (AFP) - Kamala Harris said Tuesday that Donald Trump made a “mess” of America and the Republican shot back that she was a “Marxist” in a fiery debate clash that could shift the narrative in the tight US presidential election.

The Democratic vice president and Republican former president shook hands – to the surprise of many – when they took to the podiums in the National Constitution Center in Philadelphia.

But the niceties soon ended.

Within minutes, 78-year-old Trump called her a “Marxist” and also falsely claimed that she and President Joe Biden had allowed “millions of people pouring into our country from prisons and jails, from mental institutions and insane asylums.”

Harris, 59, responded to much of Trump’s extreme language by smiling and shaking her head, before hitting back, pointing out that he was a convicted felon and calling him “extreme.”

Dismissing Trump’s boast that he had unprecedented successes as president, she said that in reality, “What we have done is clean up Donald Trump’s mess.”

“Donald Trump left us the worst unemployment since the Great Depression… the worst public health epidemic in a century (and) the worst attack on our democracy since the Civil War,” she said, referring to his management of the Covid-19 pandemic and his instigation of attempts to overthrow the 2020 election.

Their most intense exchange was on abortion, with Trump insisting that while having pushed for the end of the federal right to abortion, he wanted individual states to make their own policy.

Harris said he was telling a “bunch of lies” and called his policies “insulting to the women of America.”

The live clash on ABC News, watched by tens of millions of voters, was expected to last around 90 minutes.

- Harris gets under skin -

The last presidential debate in June doomed Biden’s reelection campaign, after he delivered a catastrophic performance against Trump. Harris took over as nominee amid Democratic fears that Biden was too old and infirm to defeat the scandal-plagued Republican.

Harris has earned a reputation in past debates and while serving as a senator for ice-cold put-downs and tough questions.

But Trump is the most brutal public speaker in US politics.

He also benefits from an incredible ability to survive any scandal – and his fervent base if anything enjoys his frequent gaffes, fabricated stories and promotion of conspiracy theories.

He has been convicted of falsifying business records to cover up an affair with an adult film star, found liable for sexual abuse, and faces trial on charges of trying to overturn the 2020 election that he lost to Biden.

But Harris clearly got under his skin by needling him on one of his favorite topics – the size of trademark rallies.

Attendees, she said, prompting an angry retort, were leaving early out of “exhaustion and boredom.”

At another moment where Trump appeared to be losing his cool, he talked at length about a debunked conspiracy theory that Haitian immigrants have been eating local people’s pets in Ohio.

“They’re eating the dogs, the people that came in, they’re eating the cats,” he said before being corrected by the ABC News moderator that the authorities in the town of Springfield have said this did not happen.

- Chance to change narrative -

With only 56 days left before the November 5 election, the intense spotlight was a rare opportunity for both candidates to shift the balance in what polls show is an almost evenly split contest.

A single zinger or gaffe could dominate TV screens and social media platforms for days to come.

And the debate was a key chance for Harris to introduce herself to more voters after only jumping into the race less than eight weeks ago, when 81-year-old Biden abruptly quit.

Trump touched down in his plane – dubbed Trump Force One – just over two hours ahead of the debate, while Harris arrived in the eastern city on Monday.

The pressure was arguably greater for Harris, America’s first female, Black and South Asian vice president, as she takes part in her first presidential debate.

Both candidates are vying to be seen as championing change.

Harris’s favorite rally slogan is “we’re not going back” to the chaos of the Trump years, while Trump is working to define Harris as responsible for many of the unpopular policies in the Biden administration.

Under the rules, the debate was being held without an audience, while the rivals’ microphones were only to be on when it was their turn to speak in order to avoid interruptions.