He also suggested that Mrs Clinton took a drugs to increase her energy ahead of last week's debate.

"I don't know what's going on with her because at the beginning of the last debate she was all pumped up and at the end it was like, uh... She could barely reach her car," he said, calling for a drug test before the final debate on Wednesday.

He described the stakes of the November 8 election in Manichean terms, warning that America would never recover from a Clinton victory.

"You have 24 days to make every dream you ever dreamed for your children, for your family for your country come true. You have 24 days, and if we don't win as I said before I don't think it's ever going to happen again, our country is going to be in a spiral that won't be stopped," he said.