President Donald Trump and Democratic Party nominee Joe Biden face off in the final presidential debate in Nashville, Tennessee on Thursday. Photo: VCG

US Democrat Joe Biden insisted Wednesday that he will tackle coronavirus from Day 1 if elected president but warned there is no magic "switch" to end the pandemic, as President Donald Trump insisted he will still win easily and dismissed his opponent as a COVID-19 alarmist.

Less than a week before decision day, Biden cast his presidential ballot in his home state of Delaware and met with health experts, as he fine-tuned his pandemic response plan, seeking to reassure voters that he would use science to fight the contagion.

"Even if I win it's going to take a lot of hard work to end this pandemic," the former vice president said in Wilmington.

"I'm not running on a false promise of being able to end this pandemic by flipping a switch," he added. "But what I can promise you is this: We'll start on Day 1 by doing the right thing. We'll let science guide our decisions."

Biden, 77, continues to campaign cautiously ahead of November 3, holding low-key events with small, socially distanced crowds that look nothing like the traditional scene of an upcoming White House race.

On Saturday, Biden is to get some star power when he's joined on the stump in Michigan by Barack Obama, whom he served as vice president. It will be their first joint in-person appearance of the 2020 race, though Obama has been delivering strategically timed broadsides at Trump throughout.

Trump, by contrast, is finishing his campaign in an extreme test of endurance, with a final attempt to catch up both in swing states and also states that he won in 2016 yet now has to defend.

After rallying supporters in three states Tuesday, Trump, 74, overnighted in a fourth - Nevada - then flew to Arizona for two more rallies.

On an airport tarmac in Bullhead City, Trump all but ignored the COVID-19 crisis and many supporters didn't bother with masks as they cheered his defiant insistence on a landslide victory on November 3, despite all the bad polls.

"It's going to be a great, great red wave," he boomed, referring to the Republican color.

"We love you! We love you!" the enthusiastic crowd chanted back.

AFP