Donald Trump declined to promise that he would "absolutely accept" the results of the election.
When asked if he would commit to accepting the result of the race, regardless of outcome, Trump responded, "I will look at it at the time."
"What I'm saying is that I will tell you at the time. I'll keep you in suspense," Trump said during the final debate at the University of Nevada, Las Vegas.
Trump's comments on Wednesday night directly contradict what he told NBC News at the first debate, that he "absolutely" would accept the results of the election. The New York billionaire's running mate Mike Pence previously promised that the Trump campaign would "absolutely accept the result of the election."
Hillary Clinton called Trump's comments "horrifying" and alleged the Republican nominee says things are "rigged" against him when things don't go his way.
"This is a mindset. This is how Donald thinks and it's funny, but it's also really troubling," she said. "That is not the way our democracy works."
It "must be expected" that presidential candidates accept the outcome of the election when they "may not like them," Clinton said.
"Let's be clear about what he is saying and what that means," she said. "He is denigrating — he is talking down our democracy and I, for one, am appalled that somebody who is the nominee of one of our two major parties would take that kind of position."
— NBC News' Hallie Jackson contributed to this report.