On the eve of the debate at Hofstra University in suburban New York, aides to Clinton have sought to cast Trump, a New York businessman and former reality TV host, as lacking the temperament and experience to serve as president.

Trump’s aides for their part have sought to reinforce voter doubts about Clinton’s trustworthiness.

The debate, the first of three face-to-face matchups between the two candidates, will begin at 9 p.m. on Monday (0100 GMT on Tuesday). It comes as opinion polls show a tight race between Clinton, a former secretary of state, and Trump, six weeks before the November 8 election.

“We’re going to have a lot of people really tuning into this election for the first time. They’re going to see these two candidates onstage,” Clinton campaign manager Robby Mook said on Sunday in an interview with ABC’s “This Week.” “I think they’re going to see that Donald Trump is unfit, unprepared, and over his head. I doubt he will have a command of the issues.”

Mook said Clinton would challenge Trump at the debate “to reveal what his plans are. You know, for example, he has not revealed any plan whatsoever to defeat ISIS (Islamic State) militants.”

Trump has said he would work closely with NATO allies to defeat Islamic State and vowed to wage a “military, cyber and financial” war against the militant group.

“Donald Trump’s been all about himself. But she’s got to tell people what she wants to do for them,” John Podesta, chairman of Clinton’s campaign, told NBC’s “Meet the Press” on Sunday.

Trump’s campaign manager, Kellyanne Conway, in a separate “This Week” interview on Sunday, attacked Clinton’s trustworthiness.

“You know, if you’re running against a Clinton, veracity is certainly always on the table,” she said. “Hillary Clinton’s casual relationship with the truth is well known to Americans. I’m sure we’ll see it on full display tomorrow night.”

Managing Expectations

The Trump campaign put to rest on Sunday the prospect that he might invite Gennifer Flowers, who had an affair with Clinton’s husband, former President Bill Clinton, to attend the debate.

After Dallas Mavericks owner Mark Cuban, a Clinton supporter and vociferous critic of Trump, tweeted that he had a “front-row” seat to watch the Hofstra debate, Trump raised the possibility in a tweet of inviting Flowers to the debate.

But Mike Pence, Trump’s running mate, told “Fox News Sunday” that Flowers would not attend the debate.

“Donald Trump was using the tweet yesterday really to mock an effort by Hillary Clinton and her campaign to really distract attention from what the American people are going to be focused on tomorrow night, which is on the issues, on the choice that we face,” Pence said.

Supporters of both candidates sought to manage expectations before the debate.

Mook said the moderator of Monday’s debate, NBC News anchor Lester Holt, should fact-check candidates’ statements, although Trump’s campaign said it should be up to American voters to gauge who they thought was telling the truth.

To prepare for the debate, Clinton has been holding mock debate sessions where longtime aide Philippe Reines plays the role of Trump.

Trump aides said their candidate, who like Clinton participated in numerous TV debates during their respective parties’ nominating races, was preparing for Monday’s event but not doing mock debates where someone plays the role of Clinton.

Trump’s advisers said the Republican presidential nominee was going up against a highly seasoned politician.

“He’s the outsider, he’s a person who has never run before, let alone be in a presidential debate, but he’s going to be ready,” said Republican National Committee Chairman Reince Priebus. “And I think one of the things Donald Trump has going for him is he’s got very good instincts.”