Donald Trump and Joe Biden have been travelling across the nation as the US election race enters its final hours.

Republican President Trump, 74, visited five battleground states while his 77-year-old Democratic challenger spoke at a campaign event in Pennsylvania - also a state where the contest is tight.

Mr Biden, a former vice-president, has a healthy national lead in the latest polls ahead of Tuesday's election.

But this is not a clear-cut case in key states which could decide the result.

More than 90 million people have already cast their ballots in early voting, putting the country on course for its highest turnout in a century.

The election comes amid the ongoing coronavirus pandemic. The US has recorded more cases and more deaths than any other country worldwide, reporting more than 81,000 new infections on Sunday alone.

Top virus expert Anthony Fauci has sharply criticised the Trump administration's handling of the pandemic, drawing a rebuke from the White House on Sunday.

The Republican president had a punishing schedule on Sunday, holding rallies in Iowa, Michigan, North Carolina and Georgia, followed later by Florida - all states where polls suggest a tighter race.

Speaking in Washington, a town in Michigan, north of Detroit, Mr Trump told his supporters that under his leadership the state's car manufacturing industry had been revived.

"The economy is now growing at the fastest rate ever recorded," he claimed.

The US economy saw record-breaking 33% growth in the third financial quarter of this year, following a record 31% contraction in the second. But economists warn the damage inflicted by the pandemic - the biggest decline in the US economy in more than 80 years - could still take years to overcome.

At a later rally in Dubuque, Iowa - joined by high-profile supporters like his daughter Ivanka and aide Hope Hicks - Mr Trump promised secure borders and more conservative judges in the courts.

Addressing Covid-19, he told supporters they had a choice between a "deadly Biden lockdown" or "a safe vaccine that ends the pandemic".

His comments came after Dr Fauci, head of the US National Institute of Allergy and Infectious Diseases, told the Washington Post newspaper that the US is "in for a whole lot of hurt" in the coming months.

Mr Biden was "taking [Covid] seriously from a public health perspective", while President Trump had a different perspective and was focusing on "the economy and reopening the country", he added.

White House spokesman Judd Deere said on Sunday that Dr Fauci's comments were "unacceptable", saying that the expert chose "to criticise the President in the media and make his political leanings known by praising the President's opponent".

Mr Biden headed to Pennsylvania, his place of birth and another key state. Mr Trump narrowly won there in 2016 but polls suggest Mr Biden is slightly ahead this year.

At a rally in Philadelphia, Mr Biden addressed the city's black community, vowing to address "systemic racism" in the US and attacking the president's handling of the pandemic - something which has disproportionately affected African Americans.

"It's almost criminal the way he's handled it," he said. "It's a mass casualty event in the black community and it's totally unnecessary."

Earlier in the day, Mr Biden also courted Latino voters with a tweet in Spanish, speaking of the separation of migrant families at the border and his response to Hurricane Maria after it hit Puerto Rico.

"President Trump has attacked the dignity of Latino families time and again," the tweet read. "This will end when I am president."

Mr Biden also addressed a report by news site Axios which said Mr Trump would declare victory on Tuesday night if it looked as if he was ahead. "The president's not going to steal this election," Mr Biden said.

Mr Trump denied the Axios report, but told journalists before his North Carolina rally that counting ballots after election day was a "terrible thing".

"I don't think it's fair that we have to wait for a long period of time after the election," he said.

Mr Biden also criticised Mr Trump for encouraging his supporters after some forced a Biden campaign bus to stop on a Texas highway, something the FBI has now confirmed it is investigating. The president tweeted on Sunday that in his opinion, "these patriots did nothing wrong."

Mr Biden's campaign said he and his running mate Kamala Harris would "fan out" to "all four corners" of Pennsylvania on Monday, joined by their partners and the pop stars Lady Gaga and John Legend.

The two rivals have radically different policies on several key issues.

On the coronavirus outbreak, Mr Trump set up a task force in January which he says has now shifted its focus to "safety and opening up our country". The president is also prioritising the speedy development of Covid treatments and vaccines, directing $10bn towards such projects.

Mr Biden wants to set up a national contact-tracing programme, establish at least 10 testing centres in every state, and provide free coronavirus testing to all. He supports a nationwide mask mandate, which would require face coverings to be worn on federal property.

On climate change, Mr Trump, being a sceptic, wants to expand non-renewable energy, and he has committed to withdrawing from the Paris Climate Accord.

Mr Biden says he would immediately re-join the Paris deal, and he also wants the US to reach net zero emissions by 2050.

On the economy, Mr Trump has pledged to create 10 million jobs in 10 months, as well as one million new small businesses. He wants to deliver an income tax cut, and provide companies with tax credits to incentivise them to keep jobs in the US.

Mr Biden wants to raise taxes for high earners to pay for investment in public services, but says the increase will only impact those earning over $400,000 a year. He supports raising the federal minimum wage to $15.

In most US presidential elections, it can take several days for every vote to be counted, but it's usually pretty clear who the winner is by the early hours of the following morning.

In 2016, Donald Trump took to the stage in New York at about 03:00 local time to give his victory speech in front of a crowd of jubilant supporters.

But don't set your alarm clocks just yet. Officials are already warning that we may have to wait longer - possibly days, even weeks - for the result this year because of the expected surge in postal ballots.

The last time the result wasn't clear within a few hours was in 2000, when the winner wasn't confirmed until a Supreme Court ruling was made a month later.

BBC