When it comes to hostile exchanges between prosecutor and felon, Kamala Harris and Donald Trump are old hands.
But Tuesday's high-stakes debate will be new territory for the Democratic vice president and her Republican rival, due to meet for the first time in front of a prime-time television audience of millions.
"The striking thing about this debate is, it's the first time in history where we'll see a prosecutor and convicted felon facing off against each other," Andrew Koneschusky, a PR expert and former press secretary for US Senate leader Chuck Schumer, told AFP.
"That's an incredible contrast. I wouldn't expect a lot of intricate policy discussion. I expect we'll see more style than substance."
Students of debating technique identify Trump, who is 78, as an avid proponent of the "Gish Gallop," named for Duane Gish.
Gish, who defended as literally true the Biblical account of the world's creation in six days, would overwhelm opponents with a dizzying torrent of rapid-fire falsehoods, distortions and distractions.
Trump – who is not known to have a granular grasp of policy – owes much of his success to this kind of filibustering, as he packs conspiracy theory, anecdote and aside into an arcane, rebuttal-proof word salad.
"It's very hard to debate someone who is quickly changing topics and not fully or truthfully answering the questions," said Flavio Hickel, a politics professor at Maryland liberal arts school Washington College.
But while the "Gish Gallop" may be good at putting opponents on the back foot, it is a risky strategy for someone trying to look presidential, analysts warn.
"As a debater, Trump brings energy, conveys certainty and strength, and never admits error, which translates for many people into presidential qualities," said Donald Nieman, a political analyst and professor at Binghamton University in New York state.
"Of course, they are likely to be coupled with transparent lies, wild exaggerations, unseemly ad hominem attacks and loopy digressions that have the opposite effect, especially on the few undecided voters."
Harris rose to the top of the Democratic ticket after 81-year-old President Joe Biden's dismal debate performance against Trump led to him dropping out of the race amid questions around his advanced years.
Analysts expect the 59-year-old Californian – "Kamala the Cop" to her admirers – to lean into her experience as a district attorney and press Trump on his role in the deadly 2021 insurrection at the US Capitol, as well as his multiple criminal cases.
"Harris is a sharp prosecutor," said Keith Gaddie, a politics professor at Texas Christian University.
"She showed her chops debating Biden and others in 2020, and will likely lean into a combination of tricks used by prosecutors to control witnesses, while also cultivating 'jury sympathy.'"
Since Harris's ascension, Democrats' messaging has evolved from presenting Trump as a powerful and existential threat to democracy to minimising him as "weird" and small.
Koneschusky expects to see more of this in the debate, but warned that Harris faces a balancing act between going after her opponent and using her precious airtime to make her own pitch for the Oval Office.
"On the one hand, this is a chance for Harris to define herself, and she needs to fully capitalise on that opportunity," he said.
"On the other hand, it's also important that Harris prosecutes the case against Trump in this debate, and she's well-equipped to do so as a former prosecutor. This is something Biden failed to do in the last debate."
One of Harris's standout debate moments came against Biden, ironically, in the 2019-20 Democratic presidential nominating contest, when she took her then-rival to task for his opposition to using federal funds to desegregate schools through busing.
"There was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day. And that little girl was me," Harris said, in a moment that immediately went viral.
But her short-lived 2020 bid for the White House also illustrated weaknesses, as when she allowed herself to be rattled by former Hawaii congresswoman Tulsi Gabbard, who savaged Harris over her record as a prosecutor.
Gabbard has switched sides and Trump has been using her in his debate prep.
The use of muted microphones during the Trump debate may meanwhile deprive Harris of another strength – her ability to shut down rivals when they try to interrupt.
Harris deployed this to full effect when Mike Pence tried to cut her off during their 2020 vice-presidential debate and she stopped him dead with an ice-cold, "Mr. Vice President, I'm speaking."
