Karen Dunn is polite, precise and barely more than five feet tall -- but after Barack Obama’s dreadful first debate against Mitt Romney in 2012, she got up in the face of the leader of the free world.

“You need to punch him in the mouth!” said Dunn.


And Obama did – delivering a powerful, campaign-stabilizing performance at Hofstra University on Long Island, the location of Monday’s critical showdown between Hillary Clinton and Donald Trump, a debate that is likely to be the most watched political event in history.

It’s not clear if Dunn and her partner Ron Klain – the two most experienced debate prep specialists in Democratic politics – are giving Hillary Clinton the same advice. But they are overseeing an orderly and intensely secretive process designed to armor a battle-scarred debater for an unpredictable face-off that presents great dangers – but also an opportunity for Clinton to reverse the fall narrative of a Trump surge.

Clinton’s team of lawyers are facing the greatest challenge of their professional lives – and that’s saying a lot, considering that Klain, Joe Biden’s former chief of staff, was tapped by Obama to solve the Ebola crisis. They know that Trump – a quick-study political novice participating in the first one-on-one debate of his life – is a wild card who can turn weeks of pouring over briefing books into mockery with a single, brilliant and bullying punch.

“The fear is that she’ll get lost in the moment, and no one is better at seizing the moment than Trump,” said a longtime adviser to both Clintons.

Indeed, that’s what’s worrying Clinton’s inner circle – that victory will come down to something like tone, which she has always struggled with, vacillating between cold and severe to thoughtful and wry. But the traditional, substantive sessions now underway are key to settling the candidate’s head, longtime aides said. "The prep matters because it gives her the confidence to know she is armed,” said one longtime Clinton ally. “She will feel more comfortable if she's prepared the way she likes to prepare.”

Clinton, for all her knowledge, polling and top-tier coaching, has always been defined not by what she’s said on the debate stage but by how she’s dealt with what her opponents have said about her. These debate moments have represented many of the biggest pivot points in Clinton’s career – from her deft parrying of Rick Lazio in 2000 to her collapse under Obama’s fire at the disastrous Nov. 2007 debate in Philadelphia that demolished her frontrunner status. With Clinton, a conventional politician trapped in the reality TV world of 2016, it’s all about the reaction shot – and the Dunn-Klain team is laboring mightily to make sure she gets it right.

No secret on the Clinton campaign has been more closely guarded than the identity of the person who is impersonating Trump in the closed-door sessions staged at Clinton’s Manhattan office and at her home in Chappaqua. Clinton’s advisers, in conversations over the last month, have repeatedly emphasized that the mock debate session, while important, is less vital than the informal law school sessions where Clinton hashes out her reactions and attacks. “It’s a moot court set-up,” said a Clinton insider. “She’s doing less of the usual mock debate sessions, with 100 people standing around, this time.”

Another added that her preparation this year “is more style than substance. They’re trying to prepare her for the different Trumps that might show up.”

On Saturday, the New York Times reported that longtime Clinton aide Phillippe Reines had been playing the role of Trump in mock sessions. Several Democrats who have spoken to the participants told POLITICO that another person playing the role of interlocutor has been campaign chairman John Podesta, a sharp-tongued veteran operator known less for bluster than behind-the-curtain scheme-spinning. The buttoned-down, courtly Klain has also stood in parrying questions with Clinton, according to people close to the situation – but both men have been less concerned with imitating Trump than preparing Clinton for the substance of the attacks, two keen attorneys framing Clinton’s reactions in the precise, disciplined language their lawyerly candidate thrives on.

“It’s an unconventional year, and he’s an unconventional candidate, so maybe preparation doesn’t matter,” said David Axelrod, a former top strategist to President Obama. “But in my experience, the candidate who comes on the stage, and can anticipate the rhythm of the thing, and knows what they want to do, has a huge advantage.”

Insiders said Clinton's debate group has tried to frame every minute on the stage as a referendum on the issue of trust -- to convince voters with doubts about Clinton to contrast those concerns with how they feel about Trump handling the nuclear codes. But there is still fear of the unknown that is the other half of the equation on stage with her.

“You’re just not sure who is going to show up, so you have to do it, you have to assume he may be aggressive, or he may lay back,” communications director Jennifer Palmieri said. “That’s hard to game out.”

Clinton’s experience and confidence can make her an intimidating person to prep -- when you count her own three dozen on-stage debates there is arguably no one in American politics with more prime-time experience. Her coaches, however, are also longtime debate aficionados -- campaign consultants Joel Benenson, Jim Margolis and Mandy Grunwald all sit in on prep, as does Palmieri, longtime attorney Bob Barnett, senior policy adviser Jake Sullivan, Podesta, occasionally Bill Clinton, younger policy aides who have helped compile the thick green binders of prep materials, and others.

Klain and Dunn, who report directly to Sullivan, not only offer an overarching strategy, but act as speechwriters -- line-writers, really -- paring down language and crafting practiced lines. “I have a tendency to want to give a deep dissertation on an issue or a problem,” said Sen. Cory Booker, who Dunn has prepped for Senate debates. “Karen knew she had to break me of the habit, but do it in a way that still allowed me to feel like I wasn’t dumbing things down. She really studied me. She already knew the language I was using out there.”

Like Clinton, Booker said he was hesitant to disgorge pre-packaged lines. But the forceful Dunn pressed him, just as she goaded Obama. “She didn’t call them ‘lines,’” he said. “She called them ‘moments.’”

Dunn has even force fed some catchphrases to the notoriously message-resistant Clinton. In the primary debate in New Hampshire last February, which coincided with opening weekend of the new Star Wars movie, Dunn penned Clinton’s sign-off: “thank you, good night, and may the force be with you.”

Clinton loves the self-education aspect of the process. But she has long despised the confrontational aspects of the mock debate dry runs, even when she’s not on the stand -- she never participated in her husband’s debate preps, a noticeable absence when she served as a top campaign adviser in every other aspect of his presidential campaigns.

During a tense prep session after Bernie Sanders’ stunning and slim win in the Mar. 8 Michigan primary, for instance, Clinton was so fed up with the criticisms being lobbed at her she decided to just do the job herself. When D.C. attorney Bob Barnett, who was playing Sanders, began peppering her with attacks in a drab hotel conference room, a clearly agitated Clinton shut the session down and declared, “How about I play Bernie?”

Over the next hour or so, Clinton – to the surprise of her staff – staged a credible and unvarnished version of Sanders’ attacks on her economic plans and close ties to Wall Street, according to two people with knowledge of the exchange.

For a time, Sullivan took the role of the former secretary of state and framed several new responses that later became a staple of Clinton’s debate routine. “It turned out to be one of the most productive sessions we had,” said a Clinton ally.

Dunn and Klain have been through the fire before – Klain was responsible for the strategy that helped John Kerry win his first debate against George W. Bush by attacking him for not catching Osama Bin Laden. And many of Obama’s top advisers, including his wife, Michelle, credit the Klain-Dunn team for his fall 2012 turnaround. Klain, known for his minutely drafted action memos, started ginning up an attack plan for the president before the first debate in Denver was even over. But it was the incongruous image of Dunn surrounded by Obama’s male-dominated staff that woke up the president with her “punch him in the mouth!” summons, a quote that, for many people, stuck.

Unlike the rest of Clinton’s debate coaches, Dunn and Klain have day jobs. Dunn, who represents Uber, Apple and Oracle in her day job as a partner at Boies, Schiller & Flexner LPP, is a top litigator (and also Huma Abedin’s personal attorney). Klain works at Revolution, LLC, a private investment firm. But there hasn't been a Democratic presidential debate without one of them involved in decades.

But coaches don't play. For Clinton, success against Trump on Monday night may have more to do with how she silently projects authority when under attack.

“If Trump can be positioned to bully her, that will probably be his biggest failing,” said another longtime Clinton insider. “And her pushing him back politely, so there’s a difference between his level and her level, that will be her biggest strength.”

In the end, it might not be anything Clinton says that matters. Many longtime aides credited the power of her reaction shot – a comically disapproving maternal glare honed from her years as a first lady enduring another long spiel by somebody else -- as one of her most valuable weapons in communicating gravitas and strength in the face of Trump’s expected insults.

If you want an insight into the attitude Clinton’s aides want her to portray, check out the latest episode of “Between Two Ferns.” Clinton’s appearance on the web comedy sketch show, which posted Thursday, shows the Democrat at her silent best -- it was quickly hailed by critics as one of her most successful interviews, and the candidate who struggles with articulating a coherent positive message didn't even say much. She sat with a bemused expression on her face while comedian Zach Galifianakis lobbed the absurd at her, asking with a deadpan whether she would have to take a leave of absence from the White House if she got pregnant, and if she was "down with TPP."

One of Clinton's finest moments in the primary debates was her non-reaction to Lincoln Chafee questioning her “ethical standards” because of her email use. When asked by moderator Anderson Cooper if she wanted to respond, Clinton smiled and shook her head.

“No,” was her terse response, and the audience roared.

