WASHINGTON (NewsNation Now) — Americans are rushing to cast ballots ahead of the November election at an unprecedented pace, early voting numbers show, indicating a possible record turnout for the showdown between President Donald Trump and Democratic rival Joe Biden.

With four weeks to go before Election Day Nov. 3, over 4 million Americans already have voted, far surpassing about 75,000 at this time in 2016, according to the U.S. 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, 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% of eligible voters, the highest rate since 1908.

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.

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 repeatedly warned against mail-in voting, with concerns that it leads to fraud.

Instances of fraud related to voting by mail (VBM) are rare, according to MIT’s Election Data and Science Lab, which has produced and curated election-related research.

“However, even many scholars who argue that fraud is generally rare agree that fraud with VBM voting seems to be more frequent than with in-person voting,” the MIT report said.

For transparency, the MIT Election Data and Science Lab is funded by Democracy Fund, the William and Flora Hewlett Foundation and The Joyce Foundation.

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.

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

In South Dakota, early voting is nearly 23% of the total turnout in 2016. It is nearly 17% of total 2016 turnout in Virginia and nearly 15% 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.”

For transparency, the United States Elections Project disseminates research and projects led by Michael McDonald, a Professor of Political Science at the University of Florida. McDonald has collaborated over the years with the Associated Press and the media’s national exit poll organization, Edison Media Research and receives no support for compiled early voting data.