Americans go to the polls Tuesday but an independent election monitor says it is unlikely they will know the result Tuesday - and it may even take days before a winner is announced.

Meanwhile, in its final preelection Electoral College outlook issued 11:00 p.m. Eastern Monday, CNN said Biden commanded 279 electoral votes to Trump's 163 based on its calculations. CNN said Biden had more paths to 270 electoral votes compared with Trump, who has never led Biden in national opinion polls.

Election 2020 is expected to be unlike any other as a result of the volume of votes cast ahead of Election Day - either through mail-in ballots or early voting, according to the U.S. Election Project, a nonpartisan website run by University of Florida professor Michael McDonald.

About 97.8 million people have voted already - or 71% of the total votes cast in the 2016 election.

Counting those votes could take longer because of state laws that govern when election officials can start processing mail-in ballots. In several states, those votes cannot be counted until Election Day, meaning an unprecedented volume of mailed-in votes won't be processed until Tuesday.

Important swing states Michigan, Pennsylvania and Wisconsin are included.

The Associated Press reported that about 300 lawsuits had been filed over the election in dozens of states. Many of them pertain to procedural changes caused by the COVID-19 pandemic - which saw a big rise in mail-in voting.

Election officials are estimating an 80% turnout this year for the election as a whole.

President Donald Trump tried to reduce the effect of early votes in court. However, judges in two states rejected lawsuits intended to stop the counting of ballots. A federal judge in Texas on Monday dismissed a Republican lawsuit aimed at disqualifying 130,000 ballots cast by "drive-through voting" in Houston and a Nevada judge dismissed a similar attempt to stop counting early votes in the Las Vegas area.

Meanwhile, the candidates visited important swing states on their last day of campaigning. Democratic nominee Joe Biden was in Ohio and Pennsylvania while Trump was looking for support in North Carolina, Pennsylvania, Wisconsin and Michigan, THe Wall Street Journal reported.

The latest Wall Street Journal/NBC News poll found that support for the two candidates in a group of 12 battleground states had remained unchanged in recent days, with Mr. Biden leading Mr. Trump, 51% to 46%. Biden has maintained a lead in most national polls.

Congressional races were also in the final stretch with Democrats hoping to expand their House majority and Republicans fighting to keep control of the Senate. Democrats and Republicans were bracing for potential legal clashes over the results.

The WSJ/NBC News poll showed that supporters of Biden were more likely to vote early or already had. Trump's backers are more likely to vote in person on Election Day.

Trump will spend Election Day at the White House, his campaign said.

The Associated Press report that Trump campaigned Monday alleging the election was rigged. The president threatened legal action to stop counting beyond Election Day. If Pennsylvania ballot counting takes several days, as is allowed, Trump charged that "cheating can happen like you have never seen."

Biden, in Pittsburgh, pushed a voting rights message to a mostly Black audience, declaring that Trump believes "only wealthy folks should vote" and describing COVID-19 as a "mass casualty event for Black Americans."

"We're done with the chaos, we're done with the tweets, the anger, the hate, the failure, the irresponsibility," said Biden. He said "the first step to beating the virus is beating Donald Trump," and he promised he would retain the nation's leading infectious disease expert, Dr. Anthony Fauci, whom the president has talked of firing, The Associated Press quoted him saying.

Trump, meanwhile, criticized news media coverage of the election. "I have been under siege illegally for three-and-a-half years. I wonder what it would be like if we didn't have all of this horrible stuff. We'd have a very, very calm situation," he said late Monday in Michigan. "People see that we fight and I'm fighting for you. I'm fighting to survive. You have to survive."

One of Biden's top legal advisers Bob Bauer pushed back at Trump's promise of mobilizing his lawyers after polls close to challenge certain ballots.

"It's very telling that President Trump is focused not on his voters but on his lawyers, and his lawyers are not going to win the election for him," Bauer said. "We are fully prepared for any legal hijinks of one kind or another. We're not worried about it."

Democrats also celebrated a decision by a federal judge to reject another last-ditch Republican effort to invalidate nearly 127,000 votes in Houston because the ballots were cast at drive-thru polling centers established during the pandemic.

Biden's team pushed into states Trump won handily in 2016, hoping to deliver an election night knockout blow that could prevent further Republican challenges.