Trump vs. Harris: What to expect from the historic debate

• Vice President Kamala Harris and Donald Trump will debate for the first time on Tuesday night.
• Their face-off comes at a critical point in the extremely close 2024 race.
• This is also Harris and Trump's first time in the same room together.

Vice President Kamala Harris and former President Donald Trump are set to face off on Tuesday in a major moment that could swing an extraordinarily close 2024 race.

This will be the first time Harris and Trump have ever met each other in person, a reminder of just how dramatically the contest changed after President Joe Biden dropped out of the race in July.

Harris enters the debate will clear momentum. Trump has struggled to settle on a clear attack against her and has lost ground since Biden's exit. Still, national polling averages show Harris has only a slight lead. In some cases, the race is even closer in the small number of swing states that will decide the election.

As of Friday, only one state, Wisconsin, where Harris leads, has a larger than 3 percentage point difference between the pair in The Washington Post's polling average. Election forecaster Nate Silver has Trump as the slight favorite to win the Electoral College and thus the presidency.

Trump hemmed and hawed over the debate rules in the wake of Biden's exit, but given Harris' momentum, he could never afford to seriously miss the face off. Just days before the debate, Harris agreed to mute the microphone of the candidate who is not speaking. Biden's team initially sought that rule change ahead of the June debate, but Harris' team had tried to push Trump into reverting back to a more free for fall format. Trump himself suggested he would be open to so-called "hot" or "open" mics, but ultimately stuck by the terms that he and Biden agreed to.

Here are the vital facts you need to know before Tuesday night's debate.

When is it and how can I watch it?

The first debate between Harris and Trump is set for Tuesday at 9 p.m. ET. ABC News will host the debate, but other major networks will offer a simulcast. The debate will stream on ABC News Live, Disney+, and Hulu. You don't even need a cable log-in for ABC News Live, which you can access here.

The debate will be 90 minutes and feature two commercial breaks.

Who are the moderators?

David Muir, anchor of ABC's flagship "World News Tonight," and Linsey Davis, who anchors the Sunday edition of "World News Tonight" are set to moderate. Both journalists have moderated presidential primary debates before but this will be their first general election debate.

Will the mics be muted?

Yes. Harris' campaign confirmed in a letter to ABC News that it would accept that a candidate's mic will be muted when it is not their turn to speak.

"Vice President Harris, a former prosecutor, will be fundamentally disadvantaged by this format, which will serve to shield Donald Trump from direct exchanges with the Vice President," the Harris campaign wrote in a letter to ABC.

Ultimately, the vice president's campaign said they accepted the rules to not "jeopardize the debate."

How else will this be different?

Like June's Biden-Trump debate, this face-off fundamentally differs from any modern major presidential debate. That's because both campaigns agreed on stiff-arming the Commission on Presidential Debates, a bipartisan group that organized presidential debates for decades. Republicans left the debate commission in 2022, but it was Biden's campaign that delivered the final blow. Like in June, there will also be no live audience. Biden's campaign said in May that muting the mics and nixing the audience would return presidential debates to an acceptable level of decorum — just about everyone agrees that the first debate in 2020 was an abject disaster as Trump repeatedly interrupted Biden.

What questions can we expect?

Only Muir, Davis, and likely a very few select people within ABC News know the exact questions. Unlike some past presidential debates, there is no theme for the night. That all being said, it is a virtual guarantee that questions related to the economy will dominate the evening.

Polls have consistently shown voters view the economy as the biggest issue in the election. But recently, Harris has cut into Trump's once wide advantage of the subject. A late August Wall Street Journal poll found that Trump had a roughly eight- percentage point advantage when voters were asked who would best handle the economy. He also held a 5-point lead on better handling inflation. His margins are good, but they are nowhere near the 20-point advantage he once had over President Joe Biden on both issues late last year.

Harris has rolled out a handful of economic plans. She has proposed giving up to $25,000 to first-time home buyers, a potential $50,000 tax credit to small business owners, and even broke with Biden by proposing a 28% capital gains tax rate for Americans who make at least $1 million— lower than the White House's proposed 39.6% top rate on capital gains.

Trump laid out his economic agenda on Thursday in a speech before the New York Economic Club. He's promising to slash regulations and largely hopes to bank on voters' nostalgia for the pre-COVID-19 economy he oversaw. Trump also announced his support for a quasi-US sovereign wealth fund, though he provided few details on how it would work.

Analysts at Goldman Sachs recently concluded that Harris' plans would grow the US economy more. While Trump, especially a return to his tariff-driven trade policy, would lead the economy to contract slightly.

What will Trump's approach be?

Trump wants to squelch Harris' momentum by portraying her rush to the center as disingenuous. He is also trying to brand her as a Communist, harkening back to a long-held GOP tactic of invoking the red scare. Just like he did before facing off against Biden, the former president has also spent the lead-up to the debate trashing ABC News. Trump is well known for what in the sports world is called "working the referees," but his attacks also lay the foundation for him to dismiss the entire debate as rigged if it doesn't go well. Trump has repeatedly said that CNN was fair during the June debate after his allies questioned whether the network could be impartial.

Trump has taken particular shots at George Stephanopoulos, host of "This Week," even though the former Clinton aide is not one of the two moderators.

How will Harris try to win?

Harris is telegraphing that she wants to end the debate with a viral moment akin to when she told Vice President Mike Pence, "Mr. Vice President, I'm speaking" when he talked over her during the 2020 vice presidential debate. Harris reminded supporters of what happened in a fundraising email titled "Do you remember this" which included a gif of the moment. Reuters reported that Harris' team "believes the debate will be watched by many as video clips on social media platforms."

She has spent the last few days in Pittsburgh, holding a mini-debate prep camp. Former Clinton aide Philippe Reines is playing Trump in mock debates, a role he also stepped into for Clinton in 2016.

What's next after the debate?

The major party vice presidential nominees, Sen. JD Vance of Ohio and Gov. Tim Walz of Minnesota, are set to debate on October 1 in New York City. CBS News will host that debate. Trump and Harris are also likely to debate again next month, though those details are still being finalized.

Voters will also soon be able to cast their ballots. North Carolina began sending out ballots on Friday. Pennsylvania, the biggest swing state of all, will kick off in-person early voting on September 16.