If Hillary Clinton wins the presidency, Donald Trump warns supporters, “It’s going to be a one-party system.”

Actually, should Clinton win, there will be at least three parties competing in the aftermath of the most divisive election contest in modern times:

Democrats will be running the White House for the fifth of seven terms of a full generation of American politics. The Republican Party, whose elders and elected leaders either repudiated Trump or distanced themselves from his rhetoric, will likely run at least half if not all of Congress. And the discontented who railed against all these powers will find themselves only more alienated from mainstream politics if the billionaire who campaigned as a winner proves to be a “loser.”

What’s unknown about this third potential constituency for a party of its own is how cohesive it might remain in the wake of Trump’s defeat, and whether even Trump could rally it once again.

“I think he’ll be small potatoes a year after the election,” says Mike Murphy, a Republican strategist who advised Sen. John McCain’s White House bids and ran a super-PAC backing Jeb Bush’s candidacy this year. “The media will give him a platform for a while right after, but will eventually figure out he is over.”

Only 24 percent of Republican and Republican-leaning voters say Trump should remain “the face” of the opposition party if Clinton wins election, Des Moines, Iowa-based pollster Ann Selzer reports.

More people — 27 percent of Republicans surveyed — say Trump running mate Mike Pence should assume the role, Selzer’s Oct. 14-17 survey for Bloomberg Politics found. And just 15 percent say House Speaker Paul Ryan, the party’s 2012 vice presidential nominee, should inherit the mantle.

While more Republicans say Trump better represents their views of what the party should stand for (51 percent, versus 33 percent for Ryan), Selzer tells Bloomberg: “That said, just 38 percent of them say they will stay loyal and follow (Trump’s) future endeavors if he does not win.” One third say they’ll follow him for a while “but probably lose interest” and 24 percent say the man who’s virtually owned cable TV news for the past 16 months would fall off their radar screens.

“Our data suggest his standing would diminish,” Selzer says.

Ryan, who has walked a fine line of endorsing Trump but ultimately refused to campaign with him — after reports of Trump boasting of sexual assaults in front of a hot mic at “Access Hollywood,” and then denying any such behavior in debates — could face an insurrection within his own House ranks angered at his failure to support the party’s presidential nominee.

Fox News host and Trump ally Sean Hannity said after this week’s debate that Ryan is a “saboteur” and needs “to be called out and replaced.” Hannity pledged to actively urge hard-line conservatives to challenge Ryan for the speakership.

“I am pointing the finger directly at people like Paul Ryan and (Senate Majority Leader] Mitch McConnell and Lindsey Graham and John McCain… and Jeb Bush and everybody else that made promises they’re not keeping” about supporting the party’s nominee, Hannity said on his radio program in August.

“Republicans are living in a dream world if they think their voters are going to stop fighting the political class,” pollster Pat Caddell, who advises Breitbart, the right-wing news site run by Trump campaign CEO Steve Bannon, told the Washington Post this week. “What has happened will metamorphosize. The American people will not go gently into the good night of obscurity.”

“I think there’s a Trump party and there’s a Republican Party,” Stuart Stevens, lead strategist for Mitt Romney’s 2012 presidential campaign, has told Bloomberg News. “I have a lot of problems squaring the two.”

The two probably cannot coexist under the same roof.

“If the GOP fully becomes the home to the Breitbart and alt-right movement, it’ll cease to be the Republican Party as we’ve known it,” Peter Wehner, director of the White House Office of Strategic Initiatives under President George W. Bush, has said. “There will be a huge crack-up beyond anything we’ve seen.”

As for Trump, “he’ll have the grip on the GOP next year that fellow national election loser Mike Dukakis had on the Democratic Party after he got wiped out in 1988,” Murphy says. “Polling shows that only one quarter of voters who say they are voting GOP really like Trump. Most are holding noses but staying with him because of GOP tribal loyalty and a contempt for Hillary Clinton.”

In the aftermath of a Trump defeat, says Murphy — preparing for Republican loss of Senate control with Trump’s fading prospects — “The party will have a warlord era now – like China in the 1920’s. But 2018 mid-terms will be good — a big chance to win back the Senate — so you’ll see the more establishment warlords fighting the more Tea Party warlords in those 2018 primaries.”

“In the 2020 world, Pence and (Texas Sen. Ted) Cruz will square off on the right and a bunch of people may fight to be the regular GOP champion. It will be a long war.”

Trump has attempted to stir his supporters with warnings that this election is “rigged” — and the national public polls since Oct. 10 portraying an average 6 percentage point advantage for Clinton over Trump in a four-way race? All wrong.

His talk of a rigged election has been widely denounced by Republicans and Democrats alike. “To suggest that he will not concede despite losing the vote and then says today that he will accept the results if he wins – that is not a joking matter,” President Barack Obama said Thursday. “That is dangerous. Because when you try to sow the seeds of doubt in people’s minds about the legitimacy of our elections, that undermines our democracy. Then you’re doing the work of our adversaries for them.”

Trump refuses to say what he’ll do in defeat. When FOX News anchor Chris Wallace asked Trump at the final presidential debate this week if he’ll keep his commitment to “absolutely accept the result of the election,” Trump said: “I will look at it at the time. I’m not looking at anything now. I’ll look at it at the time.”

The next day, as leaders within his own party decried the remark as a virtual crime against democracy, Trump doubled down: “I will totally accept the results of this great and historic presidential election, if I win,” he said. “Of course, I would accept a clear election result, but I would also reserve my right to contest or file a legal challenge in the case of a questionable result.” Then he pledged to “follow and abide by all of the rules and traditions of all of the many candidates who have come before me. Always.”

Trump, who has invested considerable social media energy in labeling his rivals and critics as “losers,” constructed his nomination with the aura of a winner — albeit winning the early primary contests with only a fractional share of contests involving at times more than 16 other candidates. It’s unclear how long his supporters will stick with another loser.

As for talk of Trump taking his brand to a new political television or online streaming channel — which some saw previewed in a debate-night “Facebook Live” production by his campaign — Murphy points to the success Sarah Palin, McCain’s 2008 running mate, had with conservative talk TV after their loss:

“Trump might start a steaming channel and try to make some noise,” says Murphy, who’s been hosting his own popular podcast during this election campaign. “He needs the fame/crowd fix like Heroin. Maybe he’ll try an ice show.”