WASHINGTON, Oct 31 (Reuters) - More than 90 million Americans have cast ballots in the U.S. presidential election, according to a tally on Saturday from the U.S. Elections Project at the University of Florida, setting the stage for the highest participation rate in over a century.

The record-breaking pace, about 65 percent of the total turnout in 2016, reflects an intense interest in the vote, in which incumbent Donald Trump , a Republican, is up against Democratic nominee JoeBiden, a former vice president.

Huge numbers of people have voted by mail or at early in-person polling sites amid concerns about exposure to the coronavirus at busy Election Day voting places.

Trump trails Biden in national opinion polls amid criticism of the Trump administrations handling of COVID-19, which has killed nearly 229,000 people in the United States, with numbers of new infections once again breaking daily records as ElectionDay nears on Tuesday.

Democrats hold a significant advantage in early voting due to their embrace of postal ballots, which Republicans have historically cast in large numbers but have shunned amid repeated and unfounded attacks by Trump, who says the system is prone to widespread fraud.

Experts have predicted turnout will easily surpass the 138 million who voted in 2016. Only 47 million votes were submitted before Election Day four years ago.

In 20 states that report party registration data, 19.9 million registered Democrats have already voted, compared with 13 million Republicans, and 10.1 million with no party affiliation. The data does not show for whom the votes were cast.

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(Reporting by Idrees Ali; Editing by Daniel Wallis)