Joe Biden and Donald Trump are set to face each other in a historic US presidential debate this week. This event could be a turning point in the 2024 election as millions of potential voters watch closely.

This debate kicks off what is expected to be a tough campaign season in a deeply divided United States. The country is still dealing with the aftermath of the chaos and violence that followed the 2020 election.

With only two debates scheduled this election cycle, Thursday's debate holds even more significance. Both candidates have intensified their personal attacks, with national polls showing them in a close race.

"This debate is crucial because it allows two well-known candidates to reintroduce themselves to the public," said Donald Nieman, a political analyst and history professor at Binghamton University in New York. "The big question is how much of the public -- beyond political enthusiasts -- will pay attention to such an early debate."

For Trump, this 90-minute debate is an opportunity to highlight concerns about 81-year-old Biden's mental fitness, although Trump, at 78, has faced similar concerns about his own age.

For Biden, this debate is a chance to emphasize the legal issues surrounding Trump and portray him as unfit for office. The president will also aim to avoid any major mistakes that could cost him the November election.

The debate comes after months of legal troubles for Trump, who is set to be sentenced on July 11 for 34 counts of falsifying business records.

Both candidates have bypassed the bipartisan commission that has organized debates since 1988. Instead, they chose CNN for the first debate, unusually early in the year, with a second debate set for September 10 on ABC.

Key topics for voters include abortion, the state of US democracy, and foreign conflicts, but inflation and border security are likely to be the main focus.

In their last debates in 2020, tensions were high, with Biden at one point telling Trump, "Will you shut up, man?" due to constant interruptions. This time, moderators have more control, with microphones muted except for the candidate speaking.

"Trump is notoriously undisciplined and is likely to struggle with not being able to dominate the event," said political scientist Nicholas Creel from Georgia College and State University. "Biden is counting on this debate to remind Americans of the chaos during Trump's presidency."

Debates now are as much about creating viral moments as they are about policy. Both candidates will aim for impactful soundbites.

"I'll be watching to see if Trump tries to appear more 'presidential,' though his campaign trail behavior suggests otherwise," said Grant Reeher, a political science professor at Syracuse University.

Biden's campaign recently released an ad attacking Trump over his criminal convictions. Meanwhile, Trump, who often struggles with detailed policy discussions, has been focusing on tone and broad themes with his team at Mar-a-Lago in Florida.

Trump would benefit from sticking to a script, emphasizing Biden's weaknesses on issues like inflation and immigration while reducing his usual bombastic style, suggested Nieman, the Binghamton analyst.

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