But the 59-year-old former prosecutor will have to strike a delicate balance if she attempts to portray herself as the candidate for change, given she has been part of the Biden-Harris administration for the past four years.

Trump, on the other hand, is expected to paint Harris as a radical left liberal and the status quo candidate, while targeting her policy U-turns on issues such as fracking (she once supported a ban but no longer does), immigration (she once described Trump’s border wall as un-American but now wants to build it) and universal healthcare (which she previously backed to woo progressives, but has since reneged on).

Trump’s attacks

It’s no secret that Trump loves going on the offensive and also has a record of gendered attacks on women. Even as recently as last Friday, the former president held a rambling 45-minute press conference in which he bizarrely brought up accusations of sexual assault against him by a woman who claims he molested her on a plane in the 1970s.

“It couldn’t have happened, it didn’t happen, and she would not have been the chosen one,” he said.

But polls also show that a growing number of women are turning off Trump, including many white women – the very cohort that helped propel him to power against Hillary Clinton in 2016.

To that end, it will be interesting to see whether he pulls any punches against Harris, whom he has already attacked on everything from her laugh and intelligence, to her racial identity.

The rules of the debate require both candidates to stand at podiums opposite each other and to enter from opposite sides. (There won’t be a live audience and microphones will be muted when the other candidate is speaking.)

That means you won’t see Trump trying to intimidate Harris by wandering around the stage as he did with Clinton during their presidential debate eight years ago – a tactic critics described as “menacing”.

The prosecutor versus the convicted felon

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In an extraordinary election with as many unprecedented moments as this one, it is easy to forget that one of the candidates has been charged with 88 criminal offences, and already been found guilty of 34 of them.

As Harris likes to remind the crowd at her campaign rallies: “I took on perpetrators of all kinds. Predators who abused women. Fraudsters who scammed consumers. Cheaters who broke the rules for their own gain. So hear me when I say: I know Donald Trump’s type.”

But to what extent will Harris lean into the “prosecutor versus convicted felon” narrative during the debate?

On the one hand, it could rattle Trump and bring out his worst defences. On the other, it could give him an easy opening to tell voters more about Harris’ patchy criminal justice record: from the police backlash she faced as a district attorney for not pursuing the death penalty against a man who murdered a police officer, to the estimated 1500 people imprisoned for marijuana-related offences while she was California attorney-general.

The economy will take centre stage

Both candidates have spent the past few days sharpening their economic messages about who could do more for the middle class. This is a no-brainer, given polls repeatedly suggest that the economy is one of the top issues for voters at this year’s election, alongside America’s immigration crisis.

Trump has promised to lead what he calls a “national economic renaissance” by increasing tariffs (including a 60 per cent tariff on imports from China and 10 per cent for other nations), creating a government efficiency commission (an idea that was pitched to him by billionaire businessman Elon Musk) and reducing immigration (which critics warn could affect labour force growth).

Harris has proposed an “opportunity economy”, which includes expanding the child tax credit (including $US6000 for newborns in their first year and $US3600 per child in middle- and lower-income families); going after price gouging at the grocery store (a proposal economists have mixed feelings about); and higher taxes for the richest Americans (although she will tax them at 28 per cent, whereas Biden was proposing 39.6 per cent).

Who serves up the word salad?

Both candidates have had their share of gaffes and cringeworthy moments over the years. Indeed, Harris has had so many that the Daily Show once created a satirical video roasting her by comparing her to the Veep character played by Julia Louis-Dreyfus. Trump has taken to showing clips of Harris’ most memorable musings at his rallies. (“We’re talking about the significance of the passage of time. The significance of the passage of time. So when you think about it, there’s the significance of the passage of time,” Harris was shown saying in a supercut – video compilation – played at a recent Montana event.)

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But the former president has also come under scrutiny for his ramblings. The latest took place during an economic speech in New York, when he was asked if he would prioritise making childcare more affordable. His response?

“Well, I would do that, and we’re sitting down. You know, I was somebody – we had, Senator Marco Rubio, and my daughter Ivanka, was so impactful on that issue. It’s a very important issue. But I think when you talk about the kind of numbers that I’m talking about – that because look, childcare is childcare, couldn’t – you know, there’s something you have to have it in this country. You have to have it.” (His answer was a lot longer than that, but you get the gist.)

Needless to say, both candidates will be at pains to avoid these types of moments, knowing how quickly they can go viral or – worse still – end a campaign. Just ask Biden.

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