When Donald Trump and Joe Biden take to the debate stage on Thursday night, it will be a reunion of sorts – although not exactly a friendly one.

A current president has never before debated his predecessor, and the bad blood between these two men will be obvious on the CNN debate stage in Atlanta.

Trump never conceded the 2020 election to President Biden and days after his supporters attacked the US Capitol, he broke with tradition by refusing to attend his opponent’s inauguration.

The two men are now facing off again for the presidency and this debate will mark the first time in this election campaign that millions of Americans are sitting up and paying attention.

The stakes are high and the tension in the room will be a notch above past tussles, as both men try to convince US voters that they deserve their ballot in November.

An unusual evening

Thursday’s debate will also mark the first time that Joe Biden and Donald Trump have appeared together since their debates four years ago. The initial encounter in 2020 was an acrimonious affair, punctuated by repeated interruptions and Mr Biden’s frustrated “Will you shut up, man?” demand.

At the start of the second debate that year, delayed by Trump’s Covid diagnosis, the two men did not even shake hands.

This time, both men are out of practice. Neither has participated in any kind of debate in nearly four years, as Trump skipped the Republican primary debates on his way to becoming the party's presumptive nominee earlier this year.

Incumbent presidents frequently come out flat-footed in their opening re-election debate - a common explanation is that they are rusty or unused to being challenged after four years in the White House bubble. In this case, however, both candidates could face that challenge.

Unlike past debates, this one will be conducted in a cable television studio without a live audience to cheer - or groan. That was a request by the Biden campaign, which reportedly was concerned after a raucous Trump town hall forum hosted by CNN last year.

The debate will also feature muted microphones for candidates during their opponent's allotted speaking time, which might prevent it from spiralling into the chaos that characterised the first Trump-Biden debate in 2020. But it also could make this version a less memorable affair.

The expectations game

If one listened only to conservative commentators, President Biden will be lucky to make it through the debate without falling asleep, freezing up or wandering around the stage in confusion.

Republicans, from Trump on down, have characterised the president as senile and infirm, a shell of the man he once was.

While these attacks have played upon very real voter concern about the durability of an octogenarian president, it also has set a low bar for Mr Biden’s performance - an expectation that he has exceeded in the past, including during his energetic State of the Union address in early March.

Trump campaign officials recently tried to nudge that bar higher, noting that Mr Biden proved himself to be very effective during the 2012 vice-presidential debate against then-congressman Paul Ryan. They have also questioned the impartiality of debate host CNN.

“Will CNN decide that they are facilitator, or will CNN become a participant?” Trump campaign manager Chris LaCivita asked on Tuesday.

Trump and his campaign have also spread claims that Mr Biden will need to rely on unspecified “performance enhancing drugs” during the debate. The notion has been vehemently denied by President Biden's team but the seeding of such rumours could lay the ground for post-debate excuses if the president gets the better of his predecessor on Thursday.

Biden campaign spokeswoman Lauren Hitt said the former president was resorting to "lies" because he is “scared of being held accountable for his toxic agenda”.

President Biden may not be the only one with an opportunity to defy expectations, however. Democrats have been warning for more than a year that Trump is obsessed with revenge and retribution, and that he is an aspiring dictator who presents an existential threat to American democracy.

Biden campaign officials have said that Trump “snapped” after his 2020 election defeat and is a different man than Americans elected in 2016.

If the former president can keep his cool for 90 minutes and soften some of his sharper edges, it may help him convince the American public that the dire warnings about a potential second Trump term in office are overblown.

“Biden has got to prove that the perception that he's too old for the job is not true,” Mike Murphy, a long-time Republican political consultant, told Americast, the BBC's podcast on US politics.

“Trump's got to prove that he is not the unlikable madman that half the country thinks he is. So it's an opportunity for both of them - but also the risk is high.”

(Source: BBC)