Anita Dunn saw an opportunity with "Dark Brandon."

The liberal meme, created by Joe Biden's most online fans as a play on the right-wing "Let's Go Brandon" code bashing the president, depicts a grinning Biden with red lasers shooting out of his eyes. After Dunn, Biden's top messaging and communications adviser, became aware of the meme, she brought it to the president -- and they jumped on an opportunity to go on the offensive in the never-ending social media meme wars.

He's nodded to Dark Brandon in official speeches, aides have shared the image on social media, and his 2024 campaign is selling $32 T-shirts emblazoned with his online alter-ego. While it's a minor part of his repertoire, it shows how Dunn -- a longtime Democratic operative and Biden confidante -- has used her influence to engage in the kind of street brawling needed to combat perceptions of the aging president and the challenge ahead as he seeks a second term.

"It fits well with who she is, which is a f**k-sh*t-up-brawler. It's not a coincidence that the stuff that came behind Dark Brandon was very much in line with Anita's way of seeing the world," Rob Flaherty, the White House's director of digital strategy, told CNN.

CNN spoke to more than a dozen current and former White House and administration officials, lawmakers and Democratic strategists -- many of whom requested anonymity to speak freely -- who paint a picture of Dunn as a deeply loyal aide with a big-picture view of Biden's strategy -- with a hand in nearly all aspects of his political life.

Her instincts for brawling are now directly intertwined with the president's political fortunes, as she bolsters an already expansive role as a presidential adviser with steering 2024 messaging from the White House. For a president who relies on a very tight circle of trusted advisers, sources say Dunn has emerged as a powerful chief political communicator, a key strategist and someone who will fight on his behalf. She takes these responsibilities on with a combination of deep experience and Biden's trust.

While sources both inside and outside the White House say no communicator is better prepared for the moment than Dunn, her messaging task ahead is massive: A high-profile candidate of Biden's age has never run before, and the president is facing low approval ratings after two years in the White House, which could be a drag on his reelection campaign. With Biden widely expected to face a familiar, but powerful, foe in former President Donald Trump, the mission facing Biden's advisers is to find a message that can resonate enough with voters to beat Trump again.

Just a third of Americans (33%) say that Biden winning in 2024 would be a step forward or a triumph for the country, per a May CNN poll conducted by SSRS. Voters also have serious questions about Biden's age -- he's 80 now, and would be 86 at the end of a potential second term. Recent Washington Post/ABC News polling indicates that nearly two-thirds of respondents feel that Biden lacks the mental sharpness (63%) or is not in good enough physical health (62%) to serve effectively as president.

Those poll numbers mean that Dunn's most important task ahead is to help the president communicate to an unconvinced American public why he deserves a second term. And that has given her a White House portfolio that is virtually unparalleled.

"The circle is small and isn't exactly expanding anytime soon. That makes voices like Anita's carry a significant amount of weight," a Biden adviser said.

Keeping things 'swimming in the same direction'

Ostensibly, Dunn's White House role centers around messaging, political strategy, oversight and crisis communication on the key issues facing the White House.

"Like the rest of the senior staff, Anita works to act on the strategies and agenda President Biden assigns for her portfolio," White House spokesman Andrew Bates said.

She's in close touch with Cabinet secretaries, members of Congress, outside groups and prospective candidates. A former Hill aide, Dunn is keenly aware of congressional dynamics, but her work inside the Obama White House has shaped her views on how to approach the daily challenges confronting the president.

"She has this perch where she spans the overall strategic plan for (Biden) and for the White House, and also communicates outward with the political apparatus of the (Democratic National Committee) and the campaign and tries to keep the entire Joe Biden enterprise swimming in the same direction," a White House aide said.

She's also playing an active role in Biden's reelection campaign strategy, with multiple sources familiar with the dynamic indicating she is spearheading 2024 political messaging from the White House and coordinating with senior campaign staff.

A former White House senior adviser put it more bluntly: When it comes to 2024, "she's running everything."

Pressed in an interview with CBS News on how she will balance those two roles, Dunn declined to comment, citing the Hatch Act.

"I'm going to be here at the White House serving the people," she said. "I'm a White House employee, and I have a government job, and I will continue to do my government job."

An eye on 2024

For an incumbent president running for reelection, there is no commodity more valuable than time, especially time spent in front of the cameras, with an audience of critics looking for signs of fatigue. And with Biden officially jumping into the 2024 race, it's expected that his current pace of activity will continue for the foreseeable future -- using the bully pulpit to highlight key policies at the White House, visiting battleground states to showcase his accomplishments and traveling abroad to meet world leaders. That makes everything he says -- and how and where he says it -- part of an implicit reelection campaign.

Dunn -- in concert with a tight circle of aides, including White House chief of staff Jeff Zients, deputy chief of staff Jen O'Malley Dillon and senior advisers Mike Donilon, Bruce Reed and Steve Ricchetti -- is key to making those decisions and how to communicate them.

For instance, Dunn was central to a recent decision to frame the president's age as a sign of wisdom and experience.

"It's a legitimate thing to raise the question of age," Biden told donors at a recent campaign fundraiser. "I hope what I've been able to bring to this job, and will continue to bring, is a little bit of wisdom."

His explicit use of that framing had Dunn's fingerprints all over it -- part of Bidenworld's effort to mitigate a weakness by tying it to legislative accomplishments that supporters believe have little precedent over the past several decades.

Multiple sources told CNN that Dunn has been a decision-maker for campaign issues such as staffing, announcement timing, headquarters location and selecting campaign leadership.

She's also recently been involved in strategically elevating the profile of Vice President Kamala Harris, making it clear internally that the West Wing needs to do a better job at bolstering Harris heading into the campaign, a source familiar with the dynamic said.

Dunn is expected to remain in her White House role but continue to advise Biden on 2024 matters, multiple sources said, with campaign manager and former White House staffer Julie Chavez Rodriguez leading the charge from the campaign side.

It's a similar model to how former President Barack Obama's top advisers coordinated between the West Wing and the campaign, and not unusual.

"You want a strategist like Anita at the White House. Reelects are about organizing, ground game, targeting digital and ads and messages to particular audiences. It is a game of execution," said Jennifer Palmieri, a longtime Democratic strategist who served as communications director during the Obama administration after Dunn.

"The most important messaging that people will judge the president on is the job he is doing at the White House," Palmieri said.

Dunn's deep loyalty and instinct to fight has also raised eyebrows outside the White House. TJ Ducklo, a 2020 Biden campaign aide who resigned from his White House role after privately threatening a reporter weeks into the administration, is expected to play a role in the 2024 campaign, a decision that has been publicly defended in a rare on-the-record statement from Dunn.

"TJ made a mistake, took responsibility for it, and paid a price," Dunn said in a statement -- in her personal capacity -- to Politico's "West Wing Playbook" last month.

One former senior White House adviser, however, called that an "unforced error" by Dunn. The former adviser asked for anonymity to speak freely without retribution.

Her allegiance to Ducklo, the adviser said, "leaves the president vulnerable and exposed to unnecessary criticism and charges of hypocrisy."

"It's in direct contradiction to the president's own values and integrity and the standards that he himself demanded of everybody in the White House," the former adviser said.

'The president trusts her counsel'

Dunn, 65, is one-half of a Washington power couple at the epicenter of Bidenworld -- husband Bob Bauer is the president's personal attorney and the lead attorney handling the special counsel investigation into classified documents found at Biden's private office and residence. Yet she has risen from roles in the Jimmy Carter White House to the Senate to building public affairs powerhouse SKDK to the 2008 Obama campaign entirely on her own, sparked by her intense preparation.

"She made preparation her friend," said veteran Democratic operative Minyon Moore, who has known Dunn for decades.

"Every time she walks in a room, she's probably more prepared than most of her counterparts. And I think that's how she was able to tackle the business very early, because they knew she had done her homework. They knew she could think through many layers. She was smart as heck. And so, you want a person like Anita in the room," Moore said.

Dunn operates largely behind the scenes -- actively eschewing Washington's social scene, social media and most television appearances.

Her loyalty to Biden was cemented when she was among a small group of advisers working toward a potential 2016 presidential run, Biden wrote in his 2017 memoir, "Promise Me, Dad." Though he ultimately decided against running, Dunn's encouragement solidified a strong level of trust, multiple people close to her say.

Dunn joined Biden's 2020 campaign as a senior adviser and is widely credited for helping turn the tide of Biden's political fortunes in that campaign's Democratic primary after she was tapped to lead the operation following a fourth-place showing in the Iowa caucuses.

She encouraged a sharper messaging posture from her desk in the center of the campaign "bullpen" workspace.

When Biden arrived in the White House, Dunn briefly joined the administration as a senior adviser before returning to SKDK in August 2021, the temporary nature of her service allowing her to skirt disclosure of a cadre of investments and high-profile clients.

She continued to advise Biden informally and rejoined the White House in May 2022 in a permanent capacity, a move requiring multimillion-dollar financial disclosures.

Dunn's omnipresence in Biden's orbit has been just as clear in the period when she was out of the White House as when she's been in. She was a constant presence on conference calls or in visits to the White House.

"The president trusts her counsel -- and there's good evidence as to why," one adviser said, pointing to her central role in his path to the presidency, loyalty during Biden's 2016 deliberations and her work inside the West Wing.

Aggressive messaging and strict discipline

Over her career, Dunn has developed a reputation as an aggressive messaging tactician with strict discipline.

She's led White House messaging efforts on legislative accomplishments, seeking to highlight the legislation's tangible impacts on real Americans, though some Democrats argue the White House has not done enough to sell those measures to the public.

"What she tries to do is find the connective tissue," said a senior administration official, who talks to Dunn regularly. "There's nobody in government that has a better big picture perspective of what's going on."

Multiple colleagues suggested Dunn can inspire a certain level of anxiety in her subordinates -- demanding a high level of results and keeping the receipts -- while also being seen as a supportive mentor. At the White House, Dunn is known for leading a weekly meeting known as "Fridays at 5," a 5 p.m. in-person convening that is met with both eye-rolling (given its timing) and appreciation. It includes the entire communications staff, from interns to press assistants to the highest levels. Dunn will lead shout-outs at the beginning of each meeting, identifying achievements and often spotlighting junior staff.

"It's really emblematic of Anita," the White House aide said. "The fact that she took it upon herself to establish this very expansive view of who's on the communications team across the entire White House and set a weekly meeting where those people get direct exposure to her, as the senior adviser to the president, is really neat."

Dunn's counsel isn't only valued inside the White House walls -- Democratic Sen. Amy Klobuchar, who ran against Biden for president in 2020, regularly seeks her advice.

"She's someone that you feel like you can trust and she's going to have your back. And I think that's why she's been such a trusted adviser to President Biden," the Minnesota senator told CNN, saying that Dunn has been a key messaging coordinator for her Senate colleagues in advancing Biden's policies.

That intense loyalty to the president is ultimately why Dunn has been given such a powerful role inside Biden's political operation.

"The people that were there and believed in him when he was counted out hold a unique bond and trust with the president. That relationship, with her obvious expertise, means she's empowered to do what she needs to do," a former colleague said.

"Few people have the experience and discipline to keep their eye on the ball like she does. She's not distracted, and she knows what messages are going to land, even if the pundits disagree," the former colleague added.