We watched 19 Trump and Biden debate performances. Here's what to expect Thursday.

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President Joe Biden and former President Donald Trump will face off Thursday night for their first debate of the 2024 presidential election, but the two will be well familiar with each other’s tactics and styles.

In the 2020 election, the two men twice debated each other — with a third canceled after Trump contracted Covid. The first, a raucous affair that featured Trump's constant interruptions and Biden labeling him a “clown” and a “liar,” and the second, a far more subdued event as the candidates made their last pitch to the voters.

In the run-up to Thursday’s debate, it’s been clear that they are anticipating a foe they know well. Trump has made sure to raise expectations for Biden, while the president and his team have been strategizing on ways to get under Trump’s skin.

In recent weeks, the Biden and Trump campaigns have each waged a public war on the other’s mental faculties in the hope of injecting doubt about whether their opponent is up to the task of leading the nation.

As the two men prepare to take the stage again, NBC News watched a combined 19 debates that Biden and Trump have taken part in, watching for their common strategies, their ticks and how they handle tough moments.

Here’s a look at those key themes to get an idea of what to expect Thursday.

Biden

While Trump’s been at the center (literally and figuratively) of every debate he’s been in, Biden’s presence has been more complicated.

As one of the front-runners in the 2020 Democratic presidential race from the start, Biden’s prominence in debates ebbed and flowed based on his standing at any particular moment. In the early debates, he clashed with key rivals — including his future vice president, Kamala Harris — who were trying to use Biden as a foil to improve their own stock.

When fights between other candidates took up the oxygen in the room, Biden receded into the background of debates. But he came roaring back with some energetic and forceful performances as he took control of the race for good around the South Carolina primary.

Leans on a good sound bite

One through line across Biden’s debating has been to lean on obviously workshopped lines in the hopes of landing a clean blow on his opponent or creating a viral moment. Right out of the gate during his final debate with Trump in October 2020, Biden pushed back on Trump’s defense of his handling of the pandemic.

“I say we’re learning to live with it,” Trump said, leading Biden to quip moments later: “He says that we’re, you know, we’re learning to live with it. People are learning to die with it.”

Just a few minutes later, Biden whipped out another line evocative of one employed by his former running mate, President Barack Obama, during his 2004 convention speech.

“I don’t look at this in terms of the way he does, blue states and red states. They’re all the United States,” Biden said.

And after calling Trump “one of the most racist presidents we’ve had in modern history,” Biden did it again.

“This guy is a dog whistle about as big as a foghorn,” he said.

A look back at his primary debates from earlier that cycle shows a similar strategy.

His back against the wall after losing Iowa and New Hampshire, Biden deployed a pithy line aimed at cutting down the momentum of Sen. Bernie Sanders, I-Vt., the darling of the progressive wing of the party, and evoking his time in the Obama administration.

“Let’s talk about progressive. Progressive is getting things done, and that’s what we got done. We got a lot done,” Biden said.

Fact-checking

Biden also has a penchant for trying to fact-check his opponent, either in real time or by breaking the fourth wall and asking viewers to go search online to bolster his point. He did so during his two debates against Trump in 2020, telling the then-president to “show the tape, put it on your website” when he denied saying he opposed fracking.

He did something similar when locked in an exchange with former New York City Mayor Michael Bloomberg, pointing to Bloomberg’s past criticism of the Affordable Care Act: “Look it up, check it out,” he told viewers.

He also tried to press his progressive opponents repeatedly on the cost of their health care policies during the broad debate over whether the party should support a "Medicare for All"-style health care plan or something more similar to Obamacare.

He repeatedly tried to point to independent fact-checkers like PolitiFact, particularly during his one-on-one with Sanders in March 2020.

Biden vs. the clock

Throughout his debates, another important relationship emerged — between Biden and the clock. Biden appears keenly aware of debate rules about timing, enough that it influences how he responds.

After Harris excoriated Biden over the issue of school busing during desegregation during the first Democratic debate, in arguably the highest-profile moment of the evening, the spotlight shifted to Biden to respond. But instead of finishing his thought — after Harris criticized him both on the issue and for working with prominent segregationist senators — Biden cut himself off in this pivotal moment.

“I supported the ERA from the very beginning. I’m the guy that extended the Voting Rights Act for 25 years,” he said of the Equal Rights Amendment.

“We got to the place where we got 98 out of 98 votes in the United States Senate doing it. I’ve also argued very strongly that we, in fact, deal with the notion of denying people access to the ballot box. I agree that everybody, once they, in fact — anyway, my time is up. I’m sorry.”

During a clash in the second debate with former Housing Secretary Julián Castro, Biden cut himself off again believing his time was up, even though Castro repeatedly blew through moderator stop signs to keep landing punches on Biden.

But with his political future on the line at the pre-South Carolina primary debate, Biden flipped the switch.

“I guess the only way to do this is jump in and speak twice as much as you should,” Biden said when future Transportation Secretary Pete Buttigieg wouldn’t cede the microphone. When philanthropist Tom Steyer tried to cut him off at the end of that answer, Biden pushed back.

“I’m not out of time. You spoke over time, and I’m going to talk,” he said.

And later on, Biden directed some ire at the moderators for trying to get him to move on.

“You cut me off all the time, but I’m not going to be quiet anymore, OK?” he said.

But with Trump known for bulldozing moderators and time rules himself, Biden sometimes decided in his back-and-forths with Trump that less is more.

“Do you want to respond to that quickly, Vice President Biden?” debate moderator Kristen Welker of NBC News asked during the final presidential matchup in 2020, after Trump criticized him about Covid.

“No,” Biden said tersely.

Trump

Upon entering the presidential race in 2015, Trump commanded a presence in debates.

On top of his trademark volatility, he’d barrel over norms and tick off shocking statements. He’d respond to attacks by nuking his opponents with insults and diminishing nicknames (“Little Marco,” “Low Energy Jeb”). Confronted in an early debate about degrading women, including by calling them “disgusting pigs” and “slobs,” Trump dramatically thrusted one finger in the air and said, “Only Rosie O’Donnell,” to great laughter in the arena. The exchange made clear that audiences would hold Trump to a different standard than typical politicians.

With some exceptions, Trump tended to walk away as dominant, unpredictable and, most often, the newsmaker of the night.

He wouldn’t let go of any slight. That included the time Sen. Marco Rubio of Florida accused Trump of having small hands.

“He hit my hands. … Look at those hands. Are they small hands?” Trump said, dramatically outstretching his hands.

In a defense of his manhood, Trump, on the national debate stage, said, “I guarantee you, there’s no problem.”

Pushing for control

Especially when it’s a one-on-one debate, Trump is visibly uncomfortable if he’s not in control. “Excuse me” is a common interjection if a moderator is trying to get him back on track or an opponent attempts to jump in.

He has the mic at the ready and injects comments as the competitor is talking, often flatly denying an opponent’s attack is factual (even if it is).

In the first debate against Biden in 2020, Trump’s interruptions were so frequent (145 times by one count) that his performance was widely viewed as overkill. (He also would be diagnosed with Covid days later.) There were moments when Biden couldn’t even complete a sentence.

Then, with Biden relatively fresh from the primary, Trump tried casting Biden as a “radical” and a “socialist.” Biden swatted that away, noting he beat Sen. Bernie Sanders: “I’m standing here facing you, old buddy.”

At one point that would later prove to be prescient, Biden predicted that Roe v. Wade was on the ballot because Trump was about to make another Supreme Court justice appointment with Amy Coney Barrett.

Trump scoffed: “You don’t know it’s on the ballot. Why is it on the ballot? … I don’t think so, there’s nothing happening there.”

Two years later, with the help of a vote from Barrett, Roe v. Wade would be overturned.

In other debates, the more personal the attack on Trump, the darker his mood seemed to become — and the more Trump tried to turn the tables. This was particularly prevalent in October 2016 just after the infamous “Access Hollywood” tape was made public, in which Trump was heard talking about women, saying if you’re a star, you can “grab ‘em by the pussy.”

At a moment when he even apologized and said he was embarrassed by his words, he repeatedly changed the subject and told Democratic presidential nominee Hillary Clinton she should feel “ashamed” for her behavior, usually in reference to her emails.

But there was a singular exchange that defined that debate and turned into one of its most-watched moments, and it had nothing to do with the firestorm around Trump for his lewd caught-on-tape comment. Clinton tried to land an attack by saying, “It’s just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country.”

To which Trump memorably deadpanned: “Because you’d be in jail.”

In that same second debate, Trump’s physicality loomed large. He stood the entire time during the town-hall-style affair, even as Clinton sat in the provided chairs each time she was finished answering a question.

At times, Trump slightly paced, drawing the viewers to him even when he was off mic. At others, he seemed to hover over Clinton as she spoke. (Clinton, in a New York Times op-ed published Tuesday, described it as “stalking.”) As a result, Trump was framed in the majority of the camera shots, even when the television audience was supposed to be focused on Clinton.

What rules?

Trump has no regard for the rules. He rolls over competitors and moderators alike. He asks his own questions of his challenger. This sometimes works to his advantage, as he manages to slip in extra points or take his challenger off topic.

In 2020, however, the dynamic seemed to work against him at times. In the first one-on-one debate against Biden in Cleveland, Trump carpet-bombed Biden with interruptions to the point that he came across as agitated and sometimes even rude. Trump attempted again and again to pose his own question directly to Biden. “Let me ask you this, Joe,” he said at one point, then started in on Biden’s son Hunter and his foreign business dealings.

Biden would often smile it off, shake his head and cast Trump as a liar. But he also broke.

“It’s hard to get any word in with this clown,” Biden said, frustrated.

At the same time, in that first onstage encounter, Trump knocked Biden off his game a couple of times, where Biden seemed to have a difficult time getting back to his train of thought. That was usually obfuscated by cross-talk as moderator Chris Wallace, then of Fox News, scolded Trump for not respecting time limits.

“I’m the moderator of this debate and I would like you to let me ask this question,” a frustrated Wallace said.

Plays the victim

It will be out of character if Trump doesn’t accuse the moderators and his opponent of ganging up on him. “But that’s OK,” he usually says following an attempted appeal to the audience that he’s so strong he can dominate even with the chips stacked against him.

In the 10th primary debate in 2016 hosted by CNN, Trump at one point fired at one of the moderators, Salem Radio Network’s Hugh Hewitt: “Are you going to ask anybody else a question? … Every single question comes to me? I know I’m good for the ratings, but it’s a little bit ridiculous.”

In 2020, it came up again: “I guess I’m debating you, not him. That’s OK, I’m not surprised.”

Trump is also quick to accuse the media of gushing over his opponents while also accusing the media of outright lying about him or covering him more harshly.

This story first appeared on NBCNews.com. More from NBC News: