IIt will be a study in contrasts of age, gender, race, temperament and politics. It will also be the first time in U.S. presidential history that a former prosecutor will stand alongside a convicted criminal on the debate stage with the White House at stake.

Vice President Kamala Harris, the Democratic candidate, has served as a trial attorney, district attorney and attorney general in California. Her Republican rival, former U.S. President Donald Trump, was found guilty on 34 counts of falsifying business records to cover up a sex scandal.

The two will face off in Philadelphia on Tuesday night in their first – and perhaps only – debate, just 75 days after Joe Biden’s dismal performance against Trump sparked a political earthquake that ultimately pushed him out of the race for the White House.

Few expect such a cataclysmic outcome this time around, but Trump has his last chance to end Harris’s extended “honeymoon” as the Democrat tries to denounce her opponent’s glaring misdeeds on television before tens of millions of voters.

“This is the first time Donald Trump has actually been cross-examined in front of the American people,” said Tara Setmayer, a former Republican communications director on Capitol Hill. “Kamala Harris’ career and experience as a prosecutor, attorney general and senator is something Trump should not underestimate in this debate.”

This will be Trump’s seventh appearance in a national election debate, making him the most experienced debater in U.S. presidential history. Against Biden in June, he repeated familiar falsehoods that largely went unchallenged. Harris is expected to be a stronger opponent and could put Trump on the defensive on facts, policy and his behavior after the 2020 election.

The 59-year-old has not shied away from supporting her career in law enforcement during the election campaign so far. In a video at the recent Democratic Party convention in Chicago, she said: “That’s our decision. Prosecutor or felon.” In a speech accepting the party’s nomination, Harris told cheering delegates: “Every day I stood proudly in the courtroom before a judge and said five words: Kamala Harris, for the people.”

She also boasted about her success in fighting sex offenders and fraudsters, telling crowds across the country, “I know Donald Trump’s guys!” Harris put that experience to good use in her memorable cross-examination of Brett Kavanaugh during the Senate confirmation hearings in 2018 after Trump, then president, nominated him as a Supreme Court justice.

But she is unlikely to attack Trump directly over his convictions – or over three other criminal cases that still hang over him. When an audience member at a rally in New Hampshire this week shouted, “Lock him up!” Harris responded, “Well, you know what? The courts will take care of it, and we’ll take care of November. How about that?”

In May, Trump became the first former U.S. president to be convicted of serious crimes when a New York jury found him guilty on all 34 counts of attempting to illegally influence the 2016 election by paying hush money to a porn star. On Friday, Judge Juan Merchan postponed Trump’s sentencing until November 26 – after the November 5 election date.

For any other candidate on the debate stage, the convictions would be a huge burden. But Trump has repeatedly mobilized his supporters by falsely claiming that the case and others related to election tampering and misuse of classified information are fabricated and politically motivated. If the issue comes up on Tuesday, he will likely portray himself as a martyr and also remind viewers that he was nearly assassinated in July.

The 90-minute face-off at the National Constitutional Center in Philadelphia will be moderated by ABC News anchors David Muir and Linsey Davis. Under rules negotiated by both campaign teams, there will be no live audience and candidates’ microphones will be muted when it is not their turn to speak.

The same rules also seemed to work in Trump’s favor when he faced Biden in Atlanta in June. Aaron Kall, debate director at the University of Michigan, said: “Trump handled the fact that there was no audience in Atlanta and the microphones were turned off just fine. Biden obviously did not.”

“He’s never debated without an audience; the same goes for Harris. When you don’t get feedback and you don’t know how things are going, you have to trust your judgment, and who has better media instincts than a reality TV host?”

Muting the microphones could not only save Trump from himself – he interrupted Biden 71 times during their first presidential debate in 2020 – but also prevent Harris from delivering sharp retorts like “I’m speaking,” a phrase she said in the vice presidential debate against Mike Pence four years ago.

Harris and Trump have never met in person and will likely take on the roles of boxer and fighter in the town of Rocky Balboa. Trump, 78, is not known for his discipline, preparation or devotion to the truth. His debate appearances, like his governing style, are typically based on gut instinct rather than thoughtful analysis.

Kall, who has participated in many presidential debates, added: “You can never write him off because he’s just everywhere and he’s kind of a shotgun caliber and when you think you’ve caught him doing one thing, he quickly moves on to something else. It’s hard to keep up with him, so she has to pick her spots.”

“He’s always been known as the more effective counter-puncher. Sometimes he doesn’t hit the first volley or attack or argument, but then when she decides to go on the offensive as the accuser and treat him that way, he can be even more deadly in response.”

Trump has struggled to find a coherent and effective line of attack against Harris since she entered the race for the presidential nomination. He accused her of being a radical leftist while suggesting that she was responsible for Biden’s more centrist political agenda. He questioned her intelligence and ethnic identity. He has also failed to find a unified line on the controversial issue of abortion rights.

Republicans will hope he will be more focused in the debates and avoid overtly sexist or racist behavior. The last time he ran against a female candidate, Hillary Clinton, in 2016, he physically stood behind her in a debate and called her “the devil” and an “evil woman.”

Larry Jacobs, director of the Center for the Study of Politics and Governance at the University of Minnesota, said: “The Harris campaign desperately wanted his microphone on because they consider him their own worst enemy, and that’s true. His attention span is very limited.

“He’s a remarkably undisciplined candidate, especially at this level, and he’s deeply uncomfortable with women and people of color. I don’t see that attitude changing. Already this campaign, he’s made some pretty offensive comments about Kamala Harris. I would have expected more of that, and it’s possible that Kamala Harris will pressure him in a way that could provoke that reaction.”

Harris is heading into the debate with momentum. After the convention concluded on August 22, her campaign announced that she had raised more than $500 million since entering the race. According to polling website 538, Harris is ahead by three percentage points in national polls, but the race is much closer in some swing states.

Simon Rosenberg, a Democratic strategist, said: “Kamala Harris is a capable politician operating at the height of her power. She will come and have a good debate, and he will most likely – if you look at his public appearances so far – say things that are ugly and shocking, and he will do further damage to an already damaged campaign.”

But the vice president could face pressure to explain her reversals on issues such as universal health care, fracking, plastic straws and decriminalizing illegal border crossings. She could face questions about the Biden-Harris administration’s economic record, particularly inflation, forcing her to defend her boss and promise to turn over a new leaf.

Lanhee Chen, a fellow for American policy studies at the Hoover Institution think tank in Stanford, California, said: “The substance of her proposals so far either completely contradicts her past or they are mostly just not really good ideas. If she is able to actually propose some new ideas in this debate and give people food for thought, that is a much better approach..”

But history shows that debates are less about policy than about memorable moments. Examples include Ronald Reagan’s “there you go again” taunts to Jimmy Carter, George HW Bush’s glance at the clock, Al Gore’s sigh, and Trump’s apparent threat to throw Clinton in jail. Political scientists continue to question whether the effects on public opinion are fleeting or persistent enough to make a difference on Election Day.

Chen, who served as political director for Mitt Romney’s 2012 presidential campaign, cited Romney’s convincing performance in the first debate against a lackluster President Barack Obama in 2012 as an example. “After that great performance in the debate against Obama in 2012, we saw a significant upswing for Romney in public and private polls,” he recalled.

“In that first debate, he made a number of points that were, in many places, well outside the margin of error. There were a few weeks of positive momentum, and then the race stalled again.”

Chen added: “The debate is not happening in a vacuum. There is the debate, but there are also world events and there is also what the campaigns do after the debate. The debate will have an impact, but that impact is likely to be short-lived and will eventually blur with other campaign events as they happen.”