Even as he has complained about unfair treatment, Trump has told supporters that he is in strong position to win reelection. The boasts have doubled as a reassurance to his political base and a basis for explaining away a potential loss.

As he has repeatedly brought up losing in recent days, he has said that only external forces could cause such an outcome. With record numbers of Americans voting early and by mail, he has seized on absentee ballots as one explanation for a potential loss.

“Who’s sending them? Who’s receiving them? Who’s bringing them back? Who’s signing them? It’s ridiculous,” Trump said at a rally Monday in Allentown, Pa. “It’s the only way we can lose, in my opinion, is massive fraud. And that’s what’s happening because all over the country you’re seeing it. Thousands and thousands of ballots.”

There is no evidence of widespread voter fraud, and several Republicans have openly said Trump could lose fairly — with some almost predicting that he will.