He alleged polling booths were being tampered with and that the US media was pushing the agenda of his Democrat rival.
The billionaire tweeted: “The election is absolutely being rigged by the dishonest and distorted media pushing Crooked Hillary – but also at many polling places – SAD.”
And after watching an unfl attering depiction of himself on TV’s Saturday Night Live, Mr Trump fumed that it was a “hit job”.
He added: “Time to retire the boring and unfunny show. Media rigging election!”
And Trump supporter Dan Bowman added: “We’re going to have a revolution and take them out of office. There’s going to be a lot of bloodshed, but that’s what it’s going to take.”
Meanwhile, a 12th woman has come forward to claim that Mr Trump sexually assaulted her.
Mum-of-three Cathy Heller, 63, said on Saturday that he tried to grab and kiss her when they met at a Mother’s Day brunch in 1997.
But Mr Trump’s running mate Mike Pence said the media should focus on revelations from the hacked campaign emails of Mrs Clinton.