Here’s a riddle for Donald Trump as he heads into his third debate with Hillary Clinton in Las Vegas tonight: What would it mean to win the debate if he’s already lost the election?

There may be no good answer. In a nip-and-tuck contest, tonight’s highly publicized matchup could be hugely consequential, providing undecided voters their last side-by-side view of the candidates before the election. But this contest isn’t close, and it’s only becoming less so.

Trump’s performance in the first debate started a polling slide for the Republican nominee that he hasn’t been able to reverse since. With less than three weeks until Election Day, Clinton is sitting on a national lead of at least seven points, a historically insurmountable advantage. She’s far enough ahead in key swing states that the campaign is looking to broaden the map, devoting new resources, for example, to Arizona, a state that’s gone Democratic only once since 1948. The FiveThirtyEight election forecast now shows Clinton has a better chance of carrying Kansas, Montana, and Texas than Trump does of winning the election.

And the latest NBC/Wall Street Journal poll shows that in the debates themselves, Clinton helped her case more than Trump, with 31% of voters saying the candidates’ first two meetings made them more likely to vote for her, while only 14% said the same of Trump. Perhaps more notably, in a contest in which many voters made up their minds early about two already-famous nominees, 52% said the debates haven’t effected their decision.

Taken together, the numbers suggest Trump needs a win tonight on a scale that a single debate performance can’t provide. But even if the goal for Trump tonight should be to close out the race by narrowing the margin and restoring some dignity to his tarnished brand, the candidate hasn’t shown any inclination to do so. He’s spent more than a week fulminating on the stump about an international conspiracy to deny him the presidency, one that he insists with zero evidence involves a massive scheme to fix the election. The claim, aimed at undermining public trust in a bedrock democratic tradition, has aroused enough alarm that President Obama felt compelled to address it yesterday: “I have never seen in my lifetime, or in modern political history, any presidential candidate trying to discredit the elections and the election process before votes have even taken place,” he said during a Rose Garden appearance with Italian Prime Minister Matteo Renzi. Trump’s fellow Republicans, including his running mate, Indiana Gov. Mike Pence, have disavowed Trump’s remarks while reaffirming the integrity of American elections.

But if Trump planned to debut a newly chastened, focused version of himself tonight, he probably wouldn’t be pulling another stunt like he did at the last debate, when he invited the women who’ve accused Bill Clinton of sexual assault to sit in his family’s box during the event. This time, he’s hosting Barack Obama’s estranged half-brother, who’s endorsed Trump.

His campaign, at least, has handed him some new material to work with. Trump on Tuesday announced a proposal to impose term limits on Members of Congress, the latest installment in a package of ethics reforms he’s rolled out in recent days. The pitch adds some grist to the outsider argument that’s helped fuel Trump’s bid since its launch last summer. In his better debate moments, the candidate has pressed that case by saying Clinton’s three decades in public life have made her a feature of a system that needs shaking up. There’s little from his past performances, though, to suggest he’ll be able to stay on topic, especially when the subject turns to the multiple allegations of sexual assault Trump’s faced (and dismissed categorically as lies) since the last debate Oct. 9 in St. Louis.

Clinton, by contrast, has the luxury of deploying a prevent defense. It’s one she’s already embraced on the trail by ceding centerstage to Trump as he implodes. The former Secretary of State has her own uncomfortable revelations to answer for tonight. Hacked emails released by WikiLeaks include transcripts of her highly-compensated Goldman Sachs speeches, which harbored no bombshells but featured Clinton addressing in warm terms an industry she’s vilified on the trail. Given the trajectory of the race, if she can effectively deflect questions about the hacked material while delivering a hopeful closing case for her candidacy, she’ll have accomplished her task.

And what do voters stand to gain by tuning in for what promises to be another night of ugliness in a campaign overflowing with ugly? Maybe, just maybe, moderator Chris Wallace of Fox News can elicit some new insight into how the next president will tackle the most pressing national demands, including the economy, a subject given surprisingly short shrift in the first two debates. The announced topics for tonight: debt and entitlements, immigration, the economy, the Supreme Court, foreign hot spots, and fitness to be president. And for those just rooting for more mudslinging, that last topic likely won’t disappoint.