With four weeks to go before Election Day, more than 4 million Americans already have voted, more than 50 times the 75,000 at this time in 2016, according to the United States Elections Project, which compiles early voting data.

The shift has been driven by an expansion of early and mail-in voting in many states as a safe way to cast a ballot during the coronavirus pandemic and an eagerness to weigh in on the political future of Trump, said Michael McDonald of the University of Florida, who administers the project.

“We’ve never seen this many people voting so far ahead of an election,” McDonald said. “People cast their ballots when they make up their minds, and we know that many people made up their minds long ago and already have a judgment about Trump.”

The early surge has led McDonald to predict a record turnout of about 150 million, representing 65 percent of eligible voters, the highest rate since 1908.

Biden leads Trump in national opinion polls, although surveys in crucial battleground states indicate a tighter race.

The numbers reported so far come from 31 states, McDonald said, and will grow rapidly as more states begin early in-person voting and report absentee mail-in totals in the next few weeks. All but about a half-dozen states allow some level of early in-person voting.

The percentage of voters who cast their ballot at a voting machine on Election Day already had been in steady decline before this year, according to the U.S. Election Assistance Commission, a federal agency.

The total number of early or mail-in votes more than doubled from nearly 25 million in 2004 to 57 million in 2016, it said, representing an increase from one in five of all ballots cast to two in five of all ballots cast.

Trump has railed against mail-in voting, making unfounded accusations that it leads to fraud. Experts have said such fraud is rare.

Those attacks by the president have shown signs of depressing Republican interest in voting by mail. Democrats have more than doubled the number of returned mail-in ballots by Republicans in seven states that report voter registration data by party, according to the Elections Project.

In the crucial battleground state of Florida, Democrats have requested more than 2.4 million mail-in ballots and returned 282,000, while Republicans have asked for nearly 1.7 million and returned more than 145,000.

A national Reuters/Ipsos poll taken last week found 5 percent of Democrats nationwide said they had already voted compared to 2 percent of Republicans. About 58 percent of Democrats planned to vote early compared to 40 percent of Republicans.

McDonald said early voting typically starts strong, then drops before surging just ahead of the election. But in some states, rates of participation already have skyrocketed a month out.

In South Dakota, early voting this year already represents nearly 23 percent of the total turnout in 2016. It is nearly 17 percent of total 2016 turnout in Virginia and nearly 15 percent of total 2016 turnout in the battleground state of Wisconsin.

“That’s just nuts,” McDonald said. “Every piece of data suggests very high turnout for this election. I think that’s just a given.”