“With Universal Mail-In Voting (not Absentee Voting, which is good), 2020 will be the most INACCURATE & FRAUDULENT Election in history,” Trump tweeted. “It will be a great embarrassment to the USA. Delay the Election until people can properly, securely and safely vote???”

The U.S. Constitution gives the power to regulate the “time, place and manner” of elections to the U.S. House and Senate, with Congress also empowered to alter the rules. Nowhere is the president granted such power.

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In addition, the Constitution spells out a hard end to a president’s term on Jan. 20 in the year following a presidential election.

As more states have turned to mail-in voting in response the pandemic, Trump has repeatedly sought to undermine the method, often with unsubstantiated claims. He has attacked mail voting nearly 70 times since late March in interviews, remarks and tweets, including at least 17 times this month, according to a tally by The Washington Post.

Trump has also argued that mail-in voting tends to hurt Republicans at the ballot box.

Amy Gardner and Elise Viebeck contributed to this report.

© Jabin Botsford/The Washington Post President Trump stops to talk to reporters as he walks to board Marine One and depart from the South Lawn at the White House on Wednesday.