ATLANTA (AP) — From her first campaigns in California to her tenure as President Joe Biden’s Vice-candidateKamala Harris has developed an aggressive but measured approach to debates.

She tries to mix punch lines with details that build a larger narrative. She might shake her head to signal her disapproval as her opponent speaks, counting on viewers to see her reaction on a split screen. And she has a tried-and-true tactic for turning debates back in her favor: She says she likes to answer a question while gathering her thoughts to explain a developing position or defend a past one.

Tuesday’s presidential debate will put the Democratic vice president’s skills to an unprecedented test. Harris faces the former president Donald Trumpthe Republican candidate, who will participate in his seventh general election debate since 2016, for an event that will be watched by tens of millions of viewers, just like Early voting begins in November elections throughout the country.

People who have run against Harris and prepared her rivals say she brings a number of advantages to the duel, including her background as a prosecutor in contrast to Trump’s role as the first US president convicted of serious crimesStill, Harris’ allies warn that Trump can be a challenging and unpredictable opponent, vacillating between political criticism, personal attacks and untruths or conspiracy theories.

“She can handle the situation,” said Marc Short, who led Republican Vice President Mike Pence’s debate preparations against Harris in the fall of 2020. “She has shown that in different environments. I would not underestimate that in any way.”

Julian Castro, a Democrat who ran against Harris for president in the 2020 primaries, said Harris combines “knowledge, poise and the ability to explain things well” to stand out in the crowded primary debates.

“Some candidates are too busy trying to be catchy and go viral,” Castro said. “She found a very good balance.”

The balance between narrative and details

A former Harris aide, who asked not to be identified to discuss her approach, said the vice president viewed the events as if they were a jury trial she would have presided over as district attorney in San Francisco, or as she would have questioned a judicial nominee on Capitol Hill as a U.S. senator. The idea, the former aide said, was always to win the debate on the merits while conveying key takeaways to more casual or unprepared viewers.

“She understands that debates are about the individual interactions themselves, but also about a broader strategy of offering a vision of what your leadership and style looks like,” said Tim Hogan, who led Senator Amy Klobuchar’s preparations for the 2020 primary debate.

Kathleen Hall Jamieson, a professor of political communication at the University of Pennsylvania, said Harris makes deductive arguments but fits them into a larger narrative – the same way she would speak to jurors.

“She puts forward a thesis and then follows it with facts, facts, facts,” Jamieson said.

Jamieson pointed to the 2020 vice presidential debate, in which Harris sharply criticized Trump’s handling of the Covid-19 pandemic and the economy, and to her most memorable primary debate in 2019, when she took aim at Biden for his comments on race and institutional racism. She linked her criticism of Biden’s record to her own biography as a young, biracial student in the early era of school integration.

“That little girl was me,” Harris said in a widely shared joke that underscored her story about court-ordered school busing that allowed non-white students to attend integrated schools.

“Most people who are good at deductive reasoning are not good at packaging that into an effective narrative,” Jamieson said. “She’s good at both.”

Land unforgettable blows

Castro said Harris had a good sense of when to strike, a trait he attributed to her experience on the court. In 2019, when several Democratic candidates were talking over each other, Harris sat back before being acknowledged by moderators.

“Hey, guys, you know what? America doesn’t want to see a food fight. They want to know how we put food on their table,” she said, taking control of the conversation and earning applause.

When Harris faced Pence in 2020, it was a mostly civil, factual debate. But she made jabs that portrayed Pence as a notorious troublemaker, just as Trump had been in his first debate with Biden.

“Mr. Vice President, I’m speaking,” she said at one point with a stern look. At another point, “If you don’t mind letting me finish, we can talk.”

Finding traps in politics

Debates sometimes forced Harris onto the defensive.

In the 2020 primaries, Tulsi Gabbard, who supports Trump this year, Harris overrun about how aggressively she pursued nonviolent drug offenders as a district attorney.

That fall, Pence sometimes made it difficult for Harris to defend Biden’s positions. Now her job will be to defend not only Biden’s record, but also her own role in it and the policies she will pursue as president.

Short, one of Pence’s top advisers, pointed out that Republicans and the media had raised questions about Harris’ more liberal positions in her 2020 primary campaign, particularly on issues such as fracking, universal health care, reparations for slavery and the treatment of migrants who cross the U.S. border illegally.

“We were surprised that she missed some opportunities (against Pence) when the conversation turned to policy,” Short said.

Timing, silence and nonverbal communication

One of her first debate victories came in 2010, when Harris was running for California Attorney General. Her opponent was asked about his plans to take his public pension while continuing to receive his salary for a public office.

“I deserve it,” said Republican Steve Cooley about the so-called “double-dipping” practice.

Harris watched in silence and mild amusement as Cooley made his statements. When the anchors recognized her, she said just seven words – “Do it, Steve. You deserve it!” – in a serious tone but with a look that expressed her sarcasm. The exchange ended up in her TV spots within days.

“Kamala Harris is quite good at nonverbal communication and knows when not to speak,” Jamieson said.

The professor said Harris often shakes her head and uses different looks to signal her disapproval while her opponent is speaking, then smiles before responding in a conversational tone or attacking.

“She undermines some of Trump’s arguments that she is a ‘bad woman’ and is being egregiously unfair because her nonverbal demeanor undermines that line of attack,” Jamieson said.

Mastering a new challenge with Trump

Despite Harris’s experience in debates, Tuesday is still a new and daunting stage for her. Democrats who usually attack Trump instead appeared on Sunday’s news to make clear that Harris faces a tall order.

“It’s going to take almost superhuman focus and discipline to deal with Donald Trump in a debate,” Transportation Secretary Pete Buttigieg, another of Harris’s 2020 opponents, said on CNN. “This is not an ordinary proposal, not because Donald Trump is a master at explaining policy ideas and how they will make people better off. It’s because he’s a master at taking any form or format that’s on television and turning it into a show that’s all about him.”

Castro noted that Trump has “a nasty and devious stage presence” that makes preparation difficult. And with ABC turning off candidates’ microphones when they’re not speaking, Harris may not have as much of an easy time producing another viral moment based on viewers having seen or heard Trump at his most outlandish.

“The best thing she can do,” Castro said, “is not to be distracted by his antics.”