The presumptive Democratic and Republican party nominees will take the debate stage in Atlanta, Georgia on Thursday evening, less than five months before the vote on November 5.

Opinion polls show President Biden and ex-President Trump remain locked in a tight race that experts say could come down to a handful of key swing states.

Here’s what you need to know about the debate and its potential impact on the campaign.

Who is taking part in the debate?

Biden, the Democratic incumbent, and his Republican challenger Trump are going up against each other for the first time in the 2024 election cycle. They last debated each other on October 22, 2020, as part of that year’s presidential race.

To participate in the debate, presidential candidates had to meet a set of criteria set out by the US news network CNN, which is hosting the event.

This included having their name on enough state ballots to reach the Electoral College threshold needed to win the presidency, and having received at least 15 percent support in four separate national polls of registered and likely voters.

Where is the debate taking place and at what time?

The debate kicks off at 9pm local time (01:00 GMT) at CNN’s studios in Atlanta.

Who is hosting the debate?

The debate will be hosted by CNN anchors Jake Tapper and Dana Bash.

What is the debate format?

The debate will last 90 minutes, with two commercial breaks, CNN said.

Biden and Trump have agreed to appear behind podiums — as opposed to being seated — and their microphones will be muted unless it is their respective turn to speak.

“While no props or pre-written notes will be allowed on the stage, candidates will be given a pen, a pad of paper and a bottle of water,” the network said.

There also will not be an audience, CNN said, in order “to ensure candidates may maximize the time allotted in the debate”.

How important are televised debates in a US presidential election?

Experts have said most voters already know for whom they plan to vote in November, so it’s unclear how much the debate will push the dial in favour of either candidate.

Still, a Pew Research Center poll from 2016 found that 63 percent of voters said the presidential debates were very or somewhat helpful in deciding which White House hopeful to cast a ballot for.

That means Biden and Trump will try to use the event to appeal to a small group of “swayable voters”, explained Alan Schroeder, a professor emeritus of journalism at Northeastern University and author of the book Presidential Debates: Risky Business on the Campaign Trail.

With Biden and Trump locked in a neck-and-neck contest, those undecided voters could prove critical, Schroeder told Al Jazeera. “Any time it’s this close, a debate can be important simply because it has the potential to break that logjam.”

Is the debate happening earlier than usual? How come?

Yes. Biden and Trump had called for the 2024 presidential debates to happen earlier in the campaign, saying they wanted to make their pitches to American voters before the early-voting period opens.

The first presidential debates are typically held in the fall months — September and October — after the Republican and Democratic parties have held conventions to officially name their nominees.

It has also been a tradition since 1988 for the dates to be set by the Commission on Presidential Debates, a non-profit sponsored by the two major parties. Late last year, the commission announced that it had selected three dates: one in mid-September and two in October.

But last month, Biden’s campaign announced plans to eschew the traditional schedule and push forward the first debate. It also trimmed the number of debates to two.

“The Commission’s schedule has debates that begin after the American people have a chance to cast their vote early, and doesn’t conclude until after tens of millions of Americans will have already voted,” the Biden campaign wrote.

It also said the commission’s model of holding debates with large, in-person audiences “simply isn’t necessary or conducive to good debates”.

What topics are set to dominate?

Many polls indicate the US economy remains the top concern for Americans ahead of the election, and the candidates will no doubt be asked about their economic platforms.

Immigration, public safety and reproductive rights will also likely be debate topics, as they too rank high among voter concerns.

Foreign policy is also a topic of interest in this year’s election, and candidates are expected to be asked about their positions towards Israel’s war in Gaza, continued support for Ukraine and competition with China.

In addition, the state of the US’s democratic institutions is high on voters’ radars and is anticipated to come up on Thursday night. Biden has accused Trump of being a threat to democracy, after the former president’s supporters stormed the US Capitol on January 6, 2021 to stop Congress from certifying the 2020 election results.

The Democrat could also try to bring up Trump’s legal cases. The Republican was found guilty last month of falsifying business documents in a New York hush-money case, making him the first former president in US history ever convicted of a crime.

But pressing Trump on his conviction and legal troubles — the ex-president faces three other criminal indictments — could be risky, according to Schroeder at Northeastern University.

“Do you try to remind the audience over and over that he’s now a convicted felon and there are other trials coming up, or does that look like overkill? Would that be something that audiences might not want to hear about?” Schroeder asked.

How many people are expected to tune in?

That remains unclear.

The new 2024 debate schedule means the first event comes at a time when relatively few Americans are paying attention to the race, which could translate to low viewership.

Viewership also fluctuates greatly based on interest in the race and the appeal of the candidates. In April, the Pew Research Center found that nearly half of all registered voters said they would replace both candidates on the ballot if they could.

After all, this year’s race is a rematch of 2020, when Biden defeated Trump to win the White House, and some voters have expressed weariness with the two candidates.

Still, Schroeder said he believes Americans will tune in to June’s debate. “Traditionally, presidential debates in the US are the second-highest rated programme after the Super Bowl.”

For example, more than 73 million people tuned in across broadcast and cable networks for the first 2020 presidential election debate between Trump and Biden.

Aside from policy, what else will people be watching for?

Elaine Kamarck, a senior fellow in governance studies at the Brookings Institution think-tank in Washington, DC, told Al Jazeera’s Inside Story in mid-May that many Americans would be on the lookout for “how vigorous each of these candidates is”.

Kamarck noted that both Biden and Trump — who are 81 and 78 years old, respectively — have faced questions about their age and capacity to serve as president for another term.

“I think the debates will show the capacity of each of these men, both of whom are older than anybody we’ve had running — ever,” she said.

Schroeder added that he would also be interested in seeing how the pair treat each other in the debate.

“Are they rude? Do they try to reach out a little bit and show some kindness or at least some humanity to the other side? Those are interesting things to watch,” he said.

How can you watch Thursday’s debate?

The debate will air on CNN channels and stream at CNN.com. In the US, it will also be available on the Max streaming platform. Other US television networks are also expected to carry the event.

When is the next debate?

Biden and Trump have agreed to a second debate on September 10, hosted by ABC News.