Republican presidential nominee Donald Trump is now accusing Democrat Hillary Clinton of election fraud, as he faces the prospect of a humiliating defeat in November.
Polls show him trailing by double digits, as many Republicans abandon their own candidate in protest, saying he's not fit to be president.
But the controversial billionaire told a Pennsylvania crowd he's confident of a win.
"The only way they can beat it, in my opinion, and I mean this 100 percent, if in certain sections of the state they cheat."
He's perhaps overstating his chances, as the Democrats have carried Pennsylvania for the past six presidential elections.
The accusation comes after Ms Clinton released details of her tax payments, while Mr Trump has repeatedly declined to make his public, saying his taxes are no one's business and they reveal little.
It is customary for US presidential candidates to make their tax returns public, although they are not required by law to do so.