Republican presidential candidate Donald Trump has said he will accept the result of the US election "if I win".
But he added he reserved the right to file a legal challenge.
His comments came after he refused to promise during the final presidential debate in Las Vegas that he would trust the outcome on November 8th if he loses.
The Republican nominee had told the audience he would keep them "in suspense".
Hillary Clinton's campaign manager Robby Mook described Donald Trump's closing speech in the final presidential debate as "dark".
Speaking in the "spin room" after the debate, Mook criticised Trump's claim he might not accept the result of the election on November 8.
"It's the darkest thing we've heard in this campaign", Mook said.
Donald Trump has refused to say if he would accept the result of the election if he loses, but could he challenge it and what would happen?
During the debate Trump said "bad hombres" needed removing from the US and branded Clinton a "nasty woman". Both sparked jokes on Twitter.
The Republican refused to say whether he will accept the result of the presidential election, saying: "I will look at it at the time."