On August 13, 2020, Trump explained his reasoning behind withholding funds from the United States Postal Service amid the COVID-19 pandemic and ahead of the general election:

They want $25 billion — billion — for the post office. Now they need that money in order to have the post office work so it can take all of these millions and millions of ballots. But if they don’t get those two items, that means you can’t have universal mail-in voting.

Trump’s Postmaster General for the USPS, Louis DeJoy, a large campaign contributor with tens of millions in assets of USPS competitors, has also been accused of dismantling the USPS ahead of the election. Days later, Trump tweeted “SAVE THE POST OFFICE!”

Trump long held that mail-in voting is rife with fraud, though he and his family vote by mail.

Business Insider – Trump admits he’s refusing to fund the US Postal Service to sabotage mail-in voting
Associated Press – Trump admits he’s blocking postal cash to stop mail-in votes
New York Magazine – Trump Admits He’s Starving the Postal Service to Sabotage Voting by Mail
The Guardian – Trump admits he is undermining USPS to make it harder to vote by mail