For Trump, the debate is perhaps his last opportunity to turn around a race that appears to be slipping away from him. His predatory comments about women and a flood of sexual assault accusations have deepened his unpopularity with women and limited his pathways to victory. His supporters remain intensely loyal, but there are few signs he’s attracting the new backers he desperately needs.

Clinton takes the stage facing challenges of her own. While the electoral map currently leans in her favor, the Democrat is facing a new round of questions about her authenticity and trustworthiness, concerns that have trailed her throughout the campaign. The hacking of her top campaign adviser’s emails revealed a candidate that is averse to apologizing, can strike a different tone in private than in public, and makes some decisions only after painstaking political deliberations.

The last in a trio of presidential debates, Wednesday’s contest in Las Vegas comes just under three weeks from Election Day and with early voting already underway in several key battleground states.

Trump has leaned on an increasingly brazen strategy in the campaign’s closing weeks, including peddling charges that the election will be rigged, despite no evidence of widespread voter fraud in U.S. presidential contests. He’s also charged that Clinton attacked and intimidated women involved with her husband’s affairs, bringing three women who accused former President Bill Clinton of unwanted sexual contact and even rape to sit in the audience for the second debate. The former president has never been charged with crimes related to the encounters, though he did settle a sexual harassment lawsuit.

Trump is bringing President Barack Obama’s half-brother, Malik Obama, as his debate guest. Clinton is bringing billionaire and frequent Trump critic Mark Cuban and Hewlett Packard Enterprise CEO Meg Whitman, one of the former secretary of state’s highest-profile Republican backers.

Clinton spokesman Brian Fallon said the Democratic nominee “will be ready for whatever scorched-earth tactics (Trump) tries” in Wednesday’s debate.

Republicans desperately hope Trump can close the campaign by focusing on Clinton’s weaknesses, a strategy some privately concede may not be enough at this point for him to win, but could help GOP Senate candidates salvage their races.

The businessman has shown flashes of renewed focus in recent days, including highlighting a senior State Department official’s request that the FBI help reduce the classification of an email from Clinton’s private server. It was to be part of a bargain that would have allowed the FBI to deploy more agents in foreign countries, though it was not immediately clear whether the State Department official or someone at the FBI first raised that prospect.

Campaigning Tuesday in Colorado, Trump called the matter “felony corruption” and worse than the Watergate scandal that brought down President Richard Nixon.

Clinton, who has meticulously prepared for the three debates at the expense of time in battleground states, visibly rattled Trump in their first showdown by using his own controversial comments about women and minorities against him. The businessman was on the defense at the start of the second debate—which came days after the release of a video in which he brags about kissing and grabbing women—but ended on stronger footing, hammering Clinton for being a creature of Washington who won’t be able to bring about change.

Trump denied in the second debate that he had made the kind of unwanted sexual advances he is heard describing on the video. His denial prompted some of the women who have since publicly accused him of assault to come forward.

The Republican has acquiesced to some advisers who pressed for him to do more serious preparations after the first debate. Still, he’s continued to eschew the mock debates and multiday prep sessions that he’s criticizing Clinton for.

“She’s been doing this for 30 years and now she has to do debate prep for five days,” Trump said. “You know what the debate prep is? It’s resting. It’s lying down and going to sleep.

Moderator Chris Wallace—the first Fox News journalist to moderate a debate—has said he plans to ask the candidates about debt and entitlements, immigration, the economy, the Supreme Court, foreign hot spots and their fitness to be president. He aims to spend 15 minutes on each topic.