LAS VEGAS — The final presidential debate may be Donald Trump's last best chance to turn around an election in which Hillary Clinton appears to be decisively pulling away.
But after scattershot performances in the two previous debates for Trump, time is running out. The GOP nominee's campaign has been sinking deeper into dark conspiracy theories, while Clinton has been trying to close her campaign on high note.
After slogging through what is widely seen as the ugliest presidential campaign in recent memory, it will be the last time Clinton and Trump meet on the same stage together — they didn't even shake each others' hands at the last debate — with just three weeks to go before Election Day.
Here are five things to watch:
1. First debate Clinton or second debate Clinton?
Clinton pummeled Donald Trump in the kickoff debate at Hofstra University, while at the second, at Washington University in St. Louis, she stepped back to engender sympathy while Trump pummeled her. Both approaches worked, with Clinton seen as the clear winner in post-debate surveys.
Clinton has eased up lately after months of attacking Trump, with aides suggesting his negative ratings are as low as they can go. She's switched gears and is trying now to channel the disgust so many Americans are feeling about an election that "makes you want to unplug the internet or just look at cat GIFs," as she said last week.
Clinton is well positioned to give Trump a finishing move. But she may opt to deflect his attacks and attempt a discussion of policy to let the contrast in their approaches speak for itself.
2. What stunt will Trump pull?
Trump's decision in the second debate to bring women who'd accused Bill Clinton of sexual assault stunned observers and, Trump allies believe, rattled Clinton. And that came before Trump declared he had removed the "shackles" of traditional political behavior he claimed had restrained him.
Now, Trump plans to bring the relative of an American killed in the Benghazi attack and, most surprisingly, Barack Obama's Kenyan half-brother, Malik, who is supporting Trump. Pundits are baffled as to why, but Trump is nothing if not surprising.
Invoking the Benghazi attack could backfire on Trump, however, as Clinton has typically responded with the compassion and restraint Trump seemed unable to give to critics like the Gold Star Khan family.
Trump may have more tricks up his sleeve — he could trot out a new Clinton accusation, dredged from the fever swamps of Internet, like his recent claim that Clinton may be on drugs.
3. Trump v. Clinton v. Wallace
Trump has directed the full power of his presidential campaign in recent days to basically yelling at the television. The candidate and his surrogates have been spending as much time complaining about media coverage as almost anything else, accusing journalists of being part of a vast global conspiracy to defame him.
The final debate's moderator, Chris Wallace, is an anchor on Republican-friendly Fox News, but that may do little to stop Trump from turning the debate into an airing of grievances.
"I mean honestly, a global conspiracy?" Fox News' Carl Cameron pressed Trump Monday. "Fox hasn't been great," Trump replied, "But you have been better than some of the others."
It's worth remembering that some of Trump's most contentious primary moments came at Fox News debates, including the dramatic first GOP debate in which Megyn Kelly pressed him right from the start on his long history of demeaning remarks towards women. That episode set the stage for Trump's angry response that Kelly had "blood coming out of her — wherever," which foreshadowed many of the gender issues that have dominated the campaign in its final weeks.
4. Game change or go home
Trump doesn't just need to win the debate, and he doesn't just need to win it big. He needs to win it in a historic rout to begin closing the gap with Clinton in the final days of the campaign (polls out Tuesday showed Clinton competitive even in deep red Texas.)
The bar for Clinton is astronomically lower. She doesn't have to do much of anything. If the debate ends as it began, she will have cleared the final major hurdle before Election Day. After Wednesday, it will take an unforeseeable disruption to change the race.
Trump will come armed with fresh ammunition. There's the alleged "quid pro quo" between the FBI and the State Department over declassifying one of Clinton's emails, and there's new revelations from the Wikileaks dump of emails stolen from Clinton campaign chair John Podesta.
5. How deep does the conspiracy go?
Trump's speeches since the last debate have fixated on the vast conspiracy, which also includes everyone from international finance to pollsters to Republican critics including House Speaker Paul Ryan.
The component that's gotten the most attention is his repeated and unsubstantiated claim that there is a wide scale plot to rig the polls and steal the election. He's suggested Ryan is part of a "sinister deal" and may be sabotaging Trump's campaign in order to run for president in 2020.
These angles unnerve Republicans. The GOP controls the governorships in most of the major swing states and officials from both parties have criticized Trump for sowing doubts about the legitimacy of an election that polls show him losing by a decisive margin. The attacks on Ryan, meanwhile, raise fears of a rift between Trump voters and Republicans opposed to his candidacy that could depress turnout or lead GOP voters to split their ticket in either direction.
The "grand conspiracy" angle is catnip for Trump's diehard supporters, but it's been difficult to sell outside of that committed group. And Trump in particular has struggled to explain its baroque patchwork of obscure players like Sidney Blumenthal and their connections to Clinton.
On the other hand, it's not clear Trump's strategy runs beyond firing up his base. Will he dig deeper into the conspiracy weeds or adjust for a different audience?