Donald Trump on Wednesday refused to say he will accept election results if he loses to Hillary Clinton, CNN.
Speaking at the Las Vegas showdown during the final debate, Republican candidate made an unprecedented statement in the weeks before a modern presidential election.
"I will look at it at the time," Trump said when asked during the final presidential debate whether he would concede if he loses on November 8, following his claims that the election is "rigged" against him.
He added: "I will keep you in suspense."
The rejection to recognize election may cast doubt on one of the fundamental principles of American politics - the peaceful, undisputed transfer of power from one president to a successor who is recognized as legitimate after winning an election.
Trump's debate performance could sway remaining undecided voters to Clinton's favour at this late stage in the campaign.
However, unlike Trump, Republican vice presidential nominee Mike Pence confirmed his recognition of the presidential election.
"We'll certainly accept the outcome of this election," he said.