Five flashpoints to watch for in Joe Biden-Donald Trump presidential debate

The ageing combatants in Thursday’s US presidential debate are well known: both are locked in a polarising, deadlocked race where allies warn the future of the republic is at stake.

But the first face-to-face meeting between President Joe Biden and Donald Trump in four years holds much that is uncharted, given the former president’s record of going off script and Biden’s contempt for his Republican rival.

Here are five things to watch for when Biden and Trump meet in Atlanta, Georgia, at 9pm ET on Thursday.

Are these men fit enough for another four years?

The 90-minute CNN broadcast will be punctuated by two advertisement breaks. It will give millions of Americans a chance to assess the stamina of both men.

Biden, 81, has been plagued by questions about his physical and mental fitness, with opinion polls showing most Americans think he is too old to be president. Trump, 78, is not much younger.

Neither candidate is allowed to take the stage with notes or other prepared materials, although they will be given a pen and paper to jot down notes.

Even so, both sides agreed to a format that intends to keep a tight control on the proceedings.

Unusually, the live broadcast will not take place before a studio audience, with the focus exclusively on the two candidates and CNN presenters Jake Tapper and Dana Bash. The candidates will be allowed two minutes for answers and one minute for rebuttals. Their microphones will be muted when they are not speaking.

Famously, the first debate between the two in the 2020 campaign was unruly — and remembered for Trump’s constant cutting in and an impatient Biden snapping at him: “Will you shut up, man?”

Trump’s interruptions were seen as detrimental to his campaign. But even with the constraints imposed on the former president, he might still try to knock Biden off his stride, or break the rules.

Will Biden target Trump over his felony convictions?

Biden has been reluctant to attack Trump over his myriad legal problems, including his New York conviction on 34 criminal charges, although Democrats have recently stepped up their references to Trump as a “convicted felon”.

The president could launch his own attacks, or use Trump’s other pending criminal trials as fodder — including one federal case and another in the state of Georgia, tied to allegations he attempted to overthrow the results of the 2020 election. Trump is also facing federal charges over his alleged mishandling of classified documents.

But it might be risky for Biden, who has legal headaches of his own, including a criminal conviction of his son, Hunter Biden, who was found guilty on three charges relating to his illegal possession of a gun. The younger Biden is staring down a separate criminal trial on tax charges, due to start later this year in California.

The president himself was investigated by the Department of Justice for his handling of classified documents. The case was dropped although the special counsel’s depiction of Biden as an “elderly man with a poor memory” did some political damage.

Biden has largely avoided commenting on his son’s legal troubles, only saying that he loves and supports him in his recovery from drug addiction. But he can expect attacks from Trump, who made Hunter Biden a feature of his 2020 campaign.

Thursday’s debate also comes as the US Supreme Court prepares to issue its decision on whether Trump will be granted legal immunity from prosecution for anything he did while serving as president — a momentous decision for the White House race.

Can Biden turn the debate to the fate of US democracy?

The president began his campaign by suggesting the coming election could be existential for US democracy. He is likely to cite Trump’s refusal to concede defeat in the 2020 election and the January 6 2021 attack by the Republican’s supporters on the US Capitol as evidence.

Trump still shies from acknowledging that Biden legitimately won the 2020 election and has recently pledged to pardon people convicted of participating in the Capitol attack. Biden will try to steer the debate to Trump’s stance on US democracy, and to depict the former president as a would-be authoritarian.

Both candidates could be asked whether they will accept the results of the election in 2024: a potentially key moment in the debate.

Who will win on the economy?

Trump will take a jab at Biden for his handling of the US economy, a persistent weak spot for the president in opinion polls. The latest FT-Michigan Ross poll found that American voters trusted Trump on the economy more than Biden — and just one in five says they are financially better off under the Democrat.

Inflation is the big topic — it rose to a multi-decade high under Biden in 2022, and is repeatedly cited in the FT-Michigan Ross poll as the biggest concern of voters. Inflation has come down in the past two years but is still too high for the Federal Reserve’s liking, meaning borrowing costs remain high. Trump has battered Biden on the campaign trail over the high cost of living.

Biden can point to millions of jobs created on his watch, record-high stock prices and his plan to invest in manufacturing across rust-belt parts of the country. He is also likely to cite his pro-union stance, contrasting that with Trump’s pledge to slash taxes for the rich and corporations.

How will immigration, abortion and war feature?

Trump has relentlessly attacked Biden over the surge in immigration across the US-Mexico border in the past three years — and can be expected to hit the issue hard on Thursday. Polls show it remains a weak point for the Democratic president, despite his recent crackdown on asylum seekers.

Biden will target Trump on abortion. The former president has repeatedly taken credit for the Supreme Court overturning of Roe vs Wade — a decision that was followed by sweeping new restrictions on abortion in some states. Biden will try to pin the restrictions on Trump and stress Democrats’ pledge to protect women’s reproductive rights.

Foreign policy could be another point of contention, with Trump likely to criticise Biden for the wars in Ukraine and Gaza. The former president has repeatedly claimed he would end both conflicts almost immediately and tried to depict Biden as a warmonger. Biden may depict his rival as too soft on Russia and naive about the Middle East.

But Biden will be conscious not to worsen the divisions within his Democratic party over his support for Israel against Hamas in Gaza. Another big dispute could be over Nato, with Biden likely to cite Trump’s threat to pull the US out of the alliance.