Just three days before the crucial Tuesday in the US presidential election, the focus of contestants Donald Trump and Joe Biden turned to the crucial Midwestern states in the race to the White House.

Trump held a rally in Michigan prior to visits to Wisconsin and Minnesota, while Biden visited Iowa before heading to those states as well on his busiest campaign days yet.

"To vote for me is to keep jobs, but to create jobs in the auto sector and all kinds of sectors in Michigan," Trump said in Waterford Township on the outskirts of Detroit, boasting of his management of the economy and warning workers in the state's auto industry that Biden's policies would threaten their jobs.

And in Iowa, where polls show intense competition between candidates, Biden said that the president's failure to contain the Corona epidemic has killed people and led to the collapse of the economy.

"One in 6 companies closed their doors because he did not act," Biden said at a rally at the fairgrounds in Des Moines, Iowa. "We cannot afford Donald Trump 4 more years."

The Coronavirus pandemic - which has killed more than 229,000 in the United States and cost millions of others their jobs - dominated the final days of the campaign.

While Trump told his supporters in recent weeks that the situation was improving even as cases increased, Biden warned of a "harsh winter" and promised new efforts to contain the virus.

Trump lagged Biden in nationwide opinion polls for several months, partly due to - according to observers - the widespread rejection of his handling of the Corona virus, as opinion polls in the most competitive states that will decide the outcome showed that the competition is more intense.

It is noteworthy that Michigan and Wisconsin are two of the 3 industrial states that usually vote for Democrats, along with Pennsylvania, but voted by a narrow margin for the Republican candidate Trump in the 2016 elections, which gave him a surprise victory over Democratic candidate Hillary Clinton.

Minnesota, which has not voted for a Republican presidential candidate since 1972, is one of the few Democratic states that Trump has been trying to change course this year, but Biden is steadily leading the polls in this state.

Biden's campaign said he and his wife would spend with Vice Presidential candidate Kamala Harris and her husband on Monday - the final day of the campaign - in Pennsylvania, enabling them to reach all corners of that divided state in the final hours of the race.

More than 85 million ballots cast their ballots either by mail or in person, which is roughly 62 percent of the total vote count in the entire 2016 election, according to the University of Florida US Election Project.

Because of the turnout by mail, the winner in several states - including critical states like Pennsylvania and Wisconsin - likely will not be known on Tuesday night, and election officials expect the counting of votes will take days.

On Thursday, a federal appeals court barred Minnesota election officials from implementing a plan to count votes that arrive within the week after Election Day, as long as they are postmarked by next Tuesday.