"We have said over and over again the stakes cannot be higher," said Allison Prasch, an expert on U.S. presidential rhetoric at the University of Wisconsin.

A Pew Research Center survey released on Monday suggests the presidential race is deadlocked. It found about half of registered voters -- 49 per cent -- said they would vote for Harris if the election were held today, and an identical share said they would back Trump.

Roneesha Stuart has not decided where her vote may land. She said it felt like Harris was backpedalling on previous stances and making promises she couldn't keep as part of President Joe Biden's administration.

"I've been on earth for 32 years and I don't think any president has ever done anything good for me. So I just want to watch. It's entertaining," Stuart said in Philadelphia on Tuesday afternoon.

The Pew report, based on a survey conducted from Aug. 26 to Sept. 2, found Trump's advantage is on the economy, with the majority of voters saying they are very or somewhat confident the former president would make good decisions about economic policy.

Harris leads on abortion and several personal traits, including being a good role model and being honest.

The economy and each leader's legacy were front and centre as the debate kicked off with both candidates making a case for their starkly different visions for the future of America.

Hundreds of supporters gathered for a Democratic watch party at the Dell Music Centre in Philadelphia cheered as Harris said Trump left behind chaos and unemployment at the end of his first administration.

"What we have done is clean up Donald Trump's mess," Harris said.

Jahmirah Brown said she thinks Harris will stand her ground.

"I feel like my girl is strong," said the 29-year-old from Delaware County, west of Philadelphia.

Harris will need to focus on her plan forward and not just reflect on Biden-era policies, said Melissa Haussman, professor emeritus at Carleton University in Ottawa. The vice-president will also need to be clear about her intentions for the economy.

"Trump, as many people have been urging, should focus on policy but I'm guessing he doesn't have the discipline or breadth of knowledge to do so. So we'll see," Haussman said.

"A good policy debate would help both, I think."

At a packed watch party organized by Philadelphia Young Republicans at a hotel not far from the National Constitution Centre where Trump and Harris were on the stage enthusiastic supporters applauded for the former president.

Trump quickly took well-known jabs at Harris saying "everyone knows she's a Marxist." He also criticized the vice-president's record on the economy with the Biden administration.

"She doesn't have a plan. She copied Biden's plan," Trump said.

Republicans said they were certain voters could see life was better under the Trump administration.

Trump's team was setting the stage Tuesday morning by releasing a new video tying the vice-president's record to decisions by President Joe Biden's administration.

"Kamala Harris has been in the White House for an unimaginable American decline. Basic goods cost more, illegal migrant crime ravages our communities, and we have lost our role as the global leader whose strength brings peace," Brian Hughes, Trump campaign senior adviser, said in a news release.

Harris's camp, on the other hand, was arguing there's a risk to democracy if there is a second Trump administration. Instead of holing up with advisers to prepare for the debate, Trump spent the weekend making claims about voter fraud and alleging he would prosecute anyone who "cheats" in the election.

"The Trump-Vance ticket is spending the days before the debate ratcheting up their dangerous lies, the same lies that inspired a mob to attack the Capitol and try to overturn the 2020 election," said Harris-Walz spokesperson Ammar Moussa in a news release.

This report by The Canadian Press was first published Sept. 10, 2024.