President Trump told the rally on Tuesday that he was fighting "Marxists" and "Lunatics" while his Democratic challenger Joe Biden accused him in Florida, another key electoral state, of treating Americans as "expensive" during the Covid 19 pandemic.

With only 21 days to go until the November 3 elections and badly down in the polls, Mr. Trump fired every lurch of exaggeration about the Democrats and every insult to Mr. Biden's mental state in his arsenal.

At the event in Pennsylvania, Mr. Trump said that Mr. Biden was "shocking like a dog" during their televised debate, called him a mental "shot," and claimed that the Democratic candidate was a communist pawn.

"He is handing over control to socialists and Marxists and left-wing extremists," said Mr. Trump to a large, raucous crowd in Johnstown. "He can't stand up to the madmen who are running his party."

Looking back at the outsider image he built for his 2016 surprise victory, billionaire developer Mr. Trump told the crowd that he was fighting a "selfish and corrupt political class" in Washington.

But even as he delighted the crowd with his greatest rhetorical hits, Mr. Trump again showed that despite his poor poll, he had no intention of trying to reach out to Democrats in a deeply divided nation.

"This is going to end up being a large-scale version of Venezuela if they get in," he said, painting a nightmarish anti-immigrant vision of a country where Democrats give free hospital care to "illegal aliens" while "decimating Medicare and destroying your social security."

The coronavirus, which claimed more than 215,000 lives in the US, was largely an afterthought, even if Mr. Trump himself had been hospitalized for three nights after a positive test at the beginning of October.

"We're going to crush the virus very quickly. It's already happening," said Mr. Trump, despite the fact that the US is now reporting large increases in infections.

"It's going to be perfect soon," he said.

Hours earlier, Mr. Biden held one of the much smaller events typical of his low-key campaign in Florida, zooming in on Mr. Trump's handling of the pandemic.

Probably even more important on election day than Pennsylvania, Florida is a battleground state that Mr. Trump won in 2016, but where the polls are currently showing Mr. Biden ahead.

Mr. Biden courted the key electoral demographics of the elderly, telling an event at a retirement center in Pembroke Pines, north of Miami, that Mr. Trump was "never focused on you."

"His handling of this pandemic has been erratic, just as his presidency has been," he said.

Mr. Biden recalled that Mr. Trump had once said that the virus-which has taken a particularly brutal toll among the elderly-" infects virtually no one.

"You're expendable, you're forgotten, you're virtually nobody. That's how he sees it," said Mr. Biden, who, unlike Mr. Trump, wore a face mask throughout his remarks.

Mr. Trump was also in Florida on Monday night for his first rally since he recovered from his Covid-19 bout. He's going to Iowa and North Carolina this week, then he's going back to Florida and Georgia.

Iowa and Georgia were two states that were handily won by Mr. Trump in 2016, but the polls show tight races in both three weeks ahead of the election.

And a poll of Florida's likely voters released by Florida Atlantic University (FAU) on Tuesday gave Mr. Biden a 51% to 47% lead.

"Joe Biden continues to compete better for senior voters than Hillary Clinton did in 2016, and that could be the difference in Florida," said Kevin Wagner, a professor of political science at the FAU.

Forty-four percent of those polled said that Mr. Trump's handling of the coronavirus crisis was good or excellent, while 50 per cent said it was poor or terrible.

Mr. Trump brushed aside the polls, calling them "fake."

Texas, meanwhile, has become the latest state to start early voting, which has been taking place at a record pace in the states so far, according to Michael McDonald, a professor at the University of Florida, who is tracking early voting.

According to the McDonald's US Elections Project, the voters have cast 11,86 million votes so far in those states that report early voting.