In final Trump-Biden showdown, less chaos but plenty of clashes

US President Donald Trump and Democratic challenger Joe Biden offered sharply contrasting views on the still-raging coronavirus pandemic at Thursday's final presidential debate.

Trump, a Republican, adopted a more restrained tone than he did during a chaotic first debate in September, when he repeatedly interrupted Biden. But Thursday's clash still featured plenty of personal attacks between two men who evinced little respect for each other, and Trump kept fact-checkers busy by levelling unfounded corruption accusations at Biden and his family.

The absence of disruptions yielded a more substantive debate over a range of topics including the economy, race, climate change, healthcare and immigration. But the coronavirus, which has killed more than 221,000 people in the United States, loomed over the proceedings as it has throughout the campaign.

The televised encounter in Nashville, Tennessee, represented one of Trump's last remaining opportunities to reshape a race that national opinion polls show he has been losing for months.

"Anyone who's responsible for that many deaths should not remain president of the United States of America," Biden said.

Trump, who has put his stewardship of the economy at the centre of his campaign, defended his approach to the outbreak and said the country could not afford to close businesses again despite fresh surges.

"We're learning to live with it," said Trump, who has played down the virus for months. "We have no choice."

"Learning to live with it?" Biden retorted. "Come on. We're dying with it."

Trump asserted that the virus was "going away," several US states reported record single-day increases in COVID-19 infections on Thursday, evidence the pandemic is accelerating anew.

Trump, whose instinct remains to run as an outsider, portrayed Biden as a career politician whose nearly 50-year record was insubstantial. But he did not lay out a clear agenda for a second term, while Biden returned again and again to Trump's four years as president, pointing to the economic damage the virus has done to people's lives.

After an opening segment on the pandemic, Thursday's clash pivoted to rapid-fire exchanges over whether either candidate had improper foreign entanglements.

Trump repeated his accusations that Biden and his son Hunter engaged in unethical practices in China and Ukraine. No evidence has been verified to support the allegations, and Biden called them false and discredited.

Trump's effort to uncover dirt on Hunter Biden's Ukraine business ties led to the president's impeachment. The president and his children have been accused of conflicts of interest of their own since he entered the White House in 2017, most involving the family's international real estate and hotel businesses.

During the debate, Biden criticized Trump's effort to persuade the U.S. Supreme Court to invalidate the 2010 Affordable Care Act, the sweeping healthcare reform passed when Biden was vice president in President Barack Obama's administration.

"People deserve to have affordable healthcare, period," Biden said, noting that the law prevented insurance companies from denying coverage to people with pre-existing conditions.

Trump said he wanted to replace the ACA with something "much better" that would offer the same protections, even though the administration has yet to propose a comprehensive healthcare plan despite a promise to do so for years.

Relatively few voters have yet to make up their minds, and Trump's window to influence the outcome may be closing. A record 47 million Americans already have cast ballots, eclipsing total early voting from the 2016 election.

The contentious first debate, when the two men traded insults, was watched by at least 73 million viewers. Trump passed up another planned debate last week after it was switched to a virtual format following his COVID-19 diagnosis.