"By far, the number one discussed issue on social media tonight was Donald Trump's unwillingness to accept the legitimacy of the results of this election," Fox host Megyn Kelly said. "Saying I'll wait and see, I'll keep you in suspense, which had the online equivalent of a jaw drop among many Republicans even."
"Considering that Governor Pence said the same thing, and so did Ivanka Trump," co-host Bret Baier agreed.
The conversation continued through a panel discussion in which Fox News analyst Brit Hume characterized Trump's refusal to commit to conceding as "the headline out of this debate."
"That doesn't happen usually in America," Hume said. "It's a big deal."
On MSNBC, Brian Williams described Trump's response as "the disqualifying moment for Americans who believe in and respect a peaceful transition of power" right after the debate ended.
It "came along with an audience gasp in the room," Williams added. "Not sure quite what we've witnessed in terms of democracy tonight, Rachel."
Co-host Rachel Maddow agreed, calling it "the moment of the debate, maybe the moment of this whole portion of the campaign."
"First time a major party candidate has done this, has said this," Williams said, adding that Trump was "making history prior to an election."
Speaking to Maddow and Williams, Republican strategist Steve Schmidt said that Trump's comments were a "clear and present danger to our constitutional order" and were "unprecedented in the history of the country."
"I think that's the headline and that's the body of the story too, in a way," Williams added.
On CNN, Wolf Blitzer called the remark "clearly the headline, Donald Trump saying he may not accept the result of this presidential election."
"One of the most stunning things I've ever heard in a presidential debate, ever," Jake Tapper agreed. "To suggest that he might not accept the results of the election that we're about to hold in fewer than three weeks was staggering."