Washington — Former President Donald Trump was set to face President Biden in their second and possibly final debate before the election. Then came the unexpected twist in July.

Mr. Biden announced on July 21 that he suspended his campaign amid growing skepticism within his own party about his ability to hold the job for another term, following his confused debate performance against Trump in June.

The debate, hosted by ABC News bee The National Constitution Center of Philadelphiais now a showdown between Vice President Kamala Harris and Trumpwho both agreed to go ahead after weeks of back and forth over the details of the event.

This is what you need to know:

What time is the debate?

The debate begins on Tuesday, September 10 at 9:00 p.m. Eastern Time.

Who moderates the presidential debate?

David Muir, host of “World News Tonight” and Linsey Davis, host of ABC News Live’s “Prime,” will moderate the debate.

Where is the presidential debate held?

The debate will take place at the National Constitution Center in Philadelphia.

Pennsylvania is one of seven battleground states that could help determine the outcome of the election. According to the latest estimate from CBS News, Harris and Trump are bound in the statewhich has 19 electors.

The last debate between Mr. Biden and Trump also took place in a swing state, Georgia. The two met in Atlanta at CNN’s studios on June 27.

What are the rules for the debate?

The campaigns and the network were working out the final rules in the days leading up to the debate. The last sticking point was via the microphones.

Harris’ campaign wanted both microphones muted for the entire event. Trump’s team wanted a candidate’s microphone muted when his opponent was speaking — a rule the Biden campaign had requested during the last debate. The Harris campaign ultimately wanted admitted.

“Vice President Harris, a former prosecutor, will be fundamentally disadvantaged by this format, which will shield Donald Trump from direct exchanges with the vice president. We suspect this is the primary reason his campaign is pushing for muted microphones,” Harris’ campaign said in a letter to ABC News.

“Despite our concerns, we understand that Donald Trump risks skipping the debate altogether, as he has previously threatened to do, if we do not agree to his preferred format,” the letter reads. “We do not want to jeopardize the debate. For that reason, we have accepted ABC’s full set of rules, including muting the microphones.”

According to Harris’ campaign, assurances were given about how any crosstalk would be handled. Microphones can be turned off if there is significant crosstalk between the candidates. A candidate who repeatedly interrupts his opponent will be warned by the moderator and his comments can be relayed to the audience. And if the microphones don’t pick up the exchanges, a group of reporters in the room will report anything of note.

ABC News reported that the microphones “are turned on only for the candidate whose turn it is to speak and are muted when it’s another candidate’s turn.” Harris and Trump are not allowed to ask each other questions.

Last month, Trump said while campaigning in Virginia that he “probably would rather let it happen, but the understanding was it would be the same as last time.”

A coin toss determined where Trump and Harris would stand onstage and the order of the closing statements. Trump won the toss and chose to deliver the final closing statement. Harris chose the lectern on the left side of the stage, meaning viewers will see her on the right side of their screens.

Candidates will each have two minutes for their closing statements. There will be no opening statements. They will have two minutes to answer questions from moderators, two minutes for rebuttals, and an additional minute for follow-ups or clarifications.

Harris and Trump are not allowed to take pre-written notes onto the podium, but they do have a pen, notepad and bottle of water with them at their podiums.

Campaign staff will not be able to interact with candidates during commercial breaks and there will be no live audience present.

Jason Miller, a senior adviser to Trump, said the campaign was “thrilled” that Harris’ team, made up largely of holdovers from Biden’s campaign, “finally accepted the already agreed-upon rules for the debate that they had initially laid out.”

What topics are under discussion?

Every topic is on the table. The network has not revealed any potential topics and is not expected to do so.

How to Watch the Presidential Debate on Cable

ABC has allowed other networks to simulcast the debate. It will air on a number of broadcast and cable networks, including CBS. Check your local listings. CBS News’ primetime coverage begins at 8 p.m. ET.

Where can you stream the presidential debate?

Viewers can also watch the debate on ABC News Live, Disney+ and Hulu. It will also be streamed on CBS News 24/7, CBSNews.com and Paramount+, with pre-debate coverage beginning on CBS News 24/7 at 5 p.m. ET.

How long will the debate last?

The 90-minute debate ends at 10:30 p.m. Eastern Time and will have two commercial breaks.

When will the next debates take place in 2024?

There is only one debate left in the election, and that is between the vice presidential nominees: Governor Tim Walz of Minnesota and Senator J.D. Vance of Ohio.

CBS News is hosting the vice presidential debatescheduled for Oct. 1 in New York City. It will be moderated by “CBS Evening News” anchor and managing editor Norah O’Donnell and “Face the Nation” moderator and CBS News chief foreign affairs correspondent Margaret Brennan.

There could be one more debate between Harris and Trump. Trump had proposed two other debates in September, in addition to the ABC News debate. Harris’ campaign said she would agree to another meeting sometime in October. The two have not yet agreed on a possible rematch date.