We've actually lived to see the day when a candidate for president, at a debate witnessed by tens of millions of viewers, would not promise to respect the result of the election.
"I will look at it at the time," Donald Trump said Wednesday, when asked by moderator Chris Wallace of Fox News whether he would accept the verdict on Nov. 8.
The media were corrupting the election by printing false news, he alleged. Millions of people were on the voters' lists who didn't belong there. The women accusing him of sexual assault were probably planted by the Clinton campaign. So he'd see what happened on election night.
"I will tell you at the time. I will keep you in suspense," the Republican nominee declared, to gasps from the audience and in living rooms across the nation and around the world.
Mr. Trump has said before that he believes the election might be rigged against him. But in previous debates, which are formal and quasi-official parts of the electoral process, he has always promised to respect the people's will.
"He is denigrating, he is talking down our democracy. And I for one am appalled," Hillary Clinton responded, but he overshadowed her this time. Whatever else has happened in the past three weeks, Mr. Trump has finally learned the art of the presidential debate. He was energetic, focused, on message and borderline treasonous.
Did he mean to do it? He must have. Will it work? How can it? But we'll have to see.
Mr. Trump was truly vicious Wednesday night. His opponent, he claimed at one point, was an unconvicted felon.
"She shouldn't be allowed to run," he accused. "She's guilty of a very very serious crime." You know – e-mails, and the Clinton Foundation and other things that have been investigated by the FBI and others, who Mr. Trump also suspects are in on the con.
Ms. Clinton fought back, quoting her former rival Senator Bernie Sanders, who said that Mr. Trump was "the most dangerous person to run for president in the modern history of America." But she seemed, at times, unable to engage, to grapple with him.
With less than three weeks to go, Mr. Trump is going to lose this election emphatically, unless he can change the game.
The RealClearPolitics compendium of polls has him more than six points behind Ms. Clinton, a virtually unleapable breach. The fivethirtyeight.com election forecast gives Ms. Clinton an 87 per cent chance of victory. Mr. Trump trails in almost every battleground state.
He had to roll the dice. Claiming the election is rigged at a televised debate is one heck of a toss.
Ms. Clinton clearly hoped to rattle Mr. Trump, as she had rattled him in past debates, with fresh allegations. But he was ready this time. She tried to tie Mr. Trump to Vladimir Putin, saying the Russian leader was clearly the architect of the WikiLeaks dump that embarrassed her campaign.
"We've never had a foreign government trying to interfere in our election," Ms. Clinton observed, quite accurately (as far as we know). Mr. Trump simply shrugged.
"She doesn't like Putin because Putin has outsmarted her every step of the way," he shot back. "If the United States got along with Russia, it wouldn't be so bad."
Ms. Clinton also accused Mr. Trump of using the very Chinese steel in his buildings that Mr. Trump has vowed to block.
"I would make it impossible for me to do that," he rebutted. Commentators reported that Mr. Trump agreed to seriously rehearse for this debate. It showed.
The debates have always been Mr. Trump's Achilles heel. In the first, Ms. Clinton got him to admit he didn't pay income tax. She simply mentioned Miss Universe 1996 and he lost it for a week. In the second, she successfully exploited the public shock over the 2005 sex-talk tape.
Now, in the third, he has refused to declare whether he will even respect the result of the election. But it was his call, his timing, his decision, not hers. She just watched.
Does he think that will actually help him? Is he right?