Combo photo shows U.S. President Donald Trump (L) and his Democratic rival Joe Biden attending their respective events on different occasions.Photo:Xinhua

US President Donald Trump vowed to again defy the polls as he sprinted through five swing states Sunday, while his opponent Joe Biden urged supporters to "take back our democracy" by voting in two days.

The last-minute scramble came as polls showed Biden maintaining his overall lead - but with some slight tightening in key states including Pennsylvania, where he leads by four points, and Florida, now a tossup, according to a RealClearPolitics average of polls.

With Americans galvanized by the stakes, the election has already mobilized a record number of early voters.

"We're now leading," Trump insisted before a raucous rally of supporters in Washington Township, Michigan. 

"Look, we're leading in Florida. We're leading in Georgia... They say it's a very close race in Texas. I don't think so. They did that four years ago and I won in a landslide."

Snow flurries fell on Trump and the crowd as the president shivered and joked repeatedly about the brisk winds and freezing conditions.

He warned, in a state long dependent on manufacturing, that Biden had "spent 47 years outsourcing your jobs, opening your borders and sacrificing American blood and treasure in endless foreign wars."

Biden and his wife Jill began the day attending Mass at their Catholic church near their home in Wilmington, Delaware. 

The former vice president spent the rest of the day in a neighboring state that is vital to both men's prospects: Pennsylvania.

At a drive-in rally in Philadelphia, Biden said: "In two days, we can put an end to a presidency that has divided this nation."

"It's time to stand up, take back our democracy," he said. "We can do this. We're better than this. We're so much better."

He also continued to hammer Trump over his handling of the coronavirus pandemic - which he called "almost criminal" in an earlier speech to supporters - following the country's worst week for new cases ever, with more than 1,000 Americans dying daily.

Yet the president has continued to shrug off the seriousness of COVID-19 - going so far as to accuse doctors of inflating virus death tolls for profit.

At his third rally of the day in Hickory, North Carolina, Trump called for businesses and schools to reopen and touted signs of a recovering economy - though economists say underlying factors do not bode well.  

His extraordinary conflict with doctor Anthony Fauci, the widely respected government expert on infectious diseases, also continued.

In an interview in the Washington Post published Saturday, Fauci said that without "an abrupt change" in the country's public health practices, Americans face "a whole lot of hurt ahead."

But he praised the Biden campaign which follows health guidance in its public events.

AFP