From Las Vegas, Nevada -

Donald Trump faced fresh criticism from Democrats and some Republicans in the Congress after saying in the third debate with Hillary Clinton that he would not immediately accept the results of the elections if he loses in November, a stance that Hillary Clinton immediately labeled as "horrifying."

"Donald Trump saying that he might not accept election results is beyond the pale," said Sen. Jeff Flake (R-AZ), one GOP Senator who has refused to support Trump's bid for the White House.

"Peaceful transfer of power and acceptance of election results is fundamental to our democracy and Constitution," said Rep. Carlos Curbelo (R-FL), who also is not supporting Trump. "This cannot be undermined ever."

Pressed by moderator Chris Wallace of Fox News during the debate, Trump twice refused to commit in advance to accepting the results of the election if he lost.

"I will look at it at the time. I'm not looking at anything now. I'll look at it at the time," Trump said.

Clinton immediately denounced Trump.

"You know, every time Donald thinks things are not going in his direction, he claims whatever it is, is rigged against him," Clinton said.

In a focus group being run during the debate, GOP strategist Frank Luntz found that Trump's answer fell flat with a group of voters.

In the Spin Room after the debate, members of Trump's team sent a slightly different message from the candidate.

"It would be wrong for a candidate to contest an election for light and transient reasons," said Sen. Jeff Sessions (R-AL), as other GOP supporters tried to downplay what Trump had said during the debate.

"The whole point tonight with Mr. Trump giving his answer, is he's putting those who might consider committing voting fraud, he's putting them on notice, that we're going to be watching," said senior Trump aide Jason Miller.

But Trump's answers even fell flat with some of his supporters in the talk radio arena.

As for Democrats, they pounced, labeling it 'unprecedented.'

"It's also dangerous and disqualifying," said Sen. Ben Cardin (D-MD).

"He's uniquely dangerous to democracy," added Sen. Brian Schatz (D-HI).

"Donald Trump shows his true colors again because he may not accept the will of American voters on November 8," said Rep. Ted Lieu (D-CA).

Trump's words also hit a nerve with some of those who teach politics at the debate site, here at the University of Nevada Las Vegas.

"At no point has any Presidential candidate said they would not accept - or even gave the suggestion of not accepting the results," said UNLV professor Dan Lee.

"That's troubling," Lee added from the post-debate Spin Room.

"It is unprecedented in American history," said UNLV professor Michael Green.