LAS VEGAS ― Unlike the first two presidential debates, the third one, at the University of Nevada, Las Vegas, is all about Hillary Clinton. And she has more than the usual simple burden of trying to win an election.

Perhaps it’s unfair ― politics is unfair ― but the state of the country and its tattered politics requires that the Democratic nominee do more than just eke out a victory.

Clinton has to win BIG, so she can at least have the chance to protect public trust in the machinery of elections, in the ability of the federal government to function, and in the credibility of American democracy.

She has to close the sale, on her own terms and on her own behalf.

If she doesn’t ― if she performs poorly in Wednesday’s debate and in the last three weeks of the campaign ― she risks a close result that could leave GOP nominee Donald Trump wounded but unbowed, and unwilling to accept the results of the Election Day count.

If she doesn’t, as president she will face a once-again divided government in Washington with no mandate and no power to deal.

“Even if she brings in a lot of Democrats with her, even if the Democrats take the Senate and even the House, it’s not going to be easy,” said Norman Ornstein, a leading author of DC governance. “But without any of that, it is hard to see how she gets anything done.”

The Clinton campaign is fully aware of the challenge ― and the opportunity.

Campaign and Democratic Party officials are working to expand the battlefield, both in terms of states Clinton might be able to win and in Senate and House races that previously were not thought close.

Even Texas, astoundingly, might now be in play in the presidential race, thanks to growing Hispanic clout that the Bush family well understands ― but that Trump has crudely dismissed.

If Democrats can win the Senate ― let alone the House ― a President Clinton would be able to bargain from a position of strength.

And that is Clinton’s challenge, starting with the debate: to keep the trend going.

And if Trump and the GOP lose badly ― very badly ― the party’s rejectionist front might be weakened enough to allow the tradition of bipartisan dealmaking to regain some momentum.

In other words, Washington might work, a little.

Clinton currently leads Trump by decent and sometimes growing margins in virtually every national poll. Big-data prognosticators, including the legendary bookmakers on the Las Vegas Strip, give her nine in 10 chances of winning the election. Her modest lead in the popular vote is amplified by the state-by-state math of the Electoral College into a projected large win.

Though trends rarely change dramatically this late in the game, it’s also true that three weeks is a lifetime in American politics, especially in the rapid-metabolism era of Twitter and Facebook.

And that is Clinton’s challenge, starting with the debate: to keep the trend going.

At this point, very little new (or worse) can be said or revealed about Trump. He is what he is. His supporters are fierce, not necessarily because they love him personally, but because they see him as a heat-seeking missile aimed at destroying the many political and financial establishments and elites they despise.

The rest of America, (and that is clearly the majority) thinks that Trump is unhinged, unqualified and unfit to be president.

In other words, Trump has all but disqualified himself.

But that, in turn, does not mean the country is eager to accept, let alone embrace, Clinton.

As much as most voters like Clinton’s policies ― her support for health care, education and women’s rights, among other things ― they see her as the two-faced, manipulative engineer of a corrupt bargain between politics and corporate money.

Even Clinton’s own advisers worry that she hasn’t not conveyed an exciting, ennobling vision of what her ascension would bring to America. So far, that hasn’t mattered much, as she has been able to keep the focus on the shortcomings of Trump.

But Clinton still needs a positive grand theme of her own, and has been unable to gain traction with one.

Meanwhile, Julian Assange’s WikiLeaks is publishing a steady stream of Clinton campaign emails unearthed (probably, the FBI says, by Russian hackers). The emails add a vivid side narration to the Clinton camp’s reputation for all-too-clever behind-the-scenes maneuvering for power and money. No one email is a “smoking gun,” but the overall smell is sour.

Young voters and minorities, who should be breaking down doors with eagerness to vote for Clinton, aren’t ― at least yet. Nor are suburbanites of all colors and kinds who can’t stomach Trump, but who are having trouble supporting Clinton.

Howard Fineman Ana Santos, 21, a politics and communications student at University of Nevada, Las Vegas, says she's undecided in the election.

Clinton must win over voters such as Ana Santos, a fourth-year student here at UNLV, where the debate will be held.

“I’m undecided,” Santos told me in the UNLV student union on Tuesday. The 21-year-old Las Vegas native, who is studying politics and communication, told me she “could never vote for Trump.”

Nor could she vote for either minor-party candidate, Libertarian Gary Johnson or the Green Party’s Jill Stein.

So she’s for Hillary, right?

“Well that is why I am undecided ― between voting and not voting,” Santos said. “I like some of her positions, but I don’t trust her. The emails … her whole history. I don’t know if I am going to vote at all.

“I’ll watch the debate.”

So will about 80 million other Americans.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.