Both candidates pressed home their core messages on the weekend as polls appeared to tighten. But they still show Biden with a lead over Trump, including in key swing states, though the outcome still appears far from certain.
Trump, who was the first out with supporters at a rally, warned that Biden would handle the pandemic by imposing endless lockdowns and damaging the economy.
He indicated Biden would mimic measures being implemented abroad.
“Europe imposed draconian lockdowns and cases were surging and deaths were surging, but think of it, draconian,” Trump told supporters in Michigan, a northern state he needs to win.
“Now, they have to do it all over again. What the hell are they doing? I think I’ll go over and explain it to them,” Trump added, pledging to never support a shutdown again.
Despite the president’s threats, most restrictions in the US are imposed by governors and local officials, not the federal government.
The US is hitting new record daily caseloads, with deaths and hospitalisations also climbing.
Public health officials are warning of a difficult winter ahead and there is growing concern the Trump administration has stopped trying to contain the outbreak, simply banking on drug companies developing therapeutics and vaccines soon.
Biden has run much of his campaign on a message of actively getting the virus under control, while rebuilding an economy which was shattered in March.
“We need a president who believes in science and listens to someone other than himself,” Biden said in one tweet, while blasting the “chaos” of the Trump administration.
“As president, I’ll build an economy that rewards work – not just wealth,” Biden added on Twitter.
The former vice president spent time on Sunday at church in Delaware, his home state, before heading to neighbouring Pennsylvania, which is becoming the key battleground.
Both candidates are presenting this election as the most important in their lifetimes, saying the very character of the country is on the ballot.
Biden has been far more cautious with regards to the coronavirus pandemic, including holding fewer and smaller rallies, while the president is trying to pack outdoor arenas as much as possible, regularly saying he enjoys greater enthusiasm
He also promised to get a dog in the White House, a dig at the incumbent who, in a rarity for a president, does not have a pet.
Trump was set to campaign in at least five states on Sunday, while Biden was focussing only on Pennsylvania, an eastern swing state which both candidates see as a must-win.
Biden got a boost from Barack Obama, the former president, who helped him campaign in Michigan on Saturday.
The northern state narrowly voted for Trump in 2016, but Biden leads in polls. Obama is also due in Georgia on Monday, as Democrats seek inroads in the Deep South.
There are also growing worries about potential for violence on or after election day, with shops in some areas boarding up their shopfronts and police gearing up for confrontations.
One incident getting attention took place at the weekend in Texas, where a convoy of cars driven by Trump supporters appears to have intimidated a Biden campaign bus on the highway, endangering the occupants of the bus, by driving overly close to it.
Trump issued a tweet late on Saturday, showing video of the trucks and cars ambushing and surrounding the bus. The video had a pro-Republican rap song. He also expressed his love for Texas. No major Republican national figure has clearly condemned the incident.
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