Symone Sanders was deeply upset in May when the graphic video of Ahmaud Arbery being shot while jogging surfaced, and she made sure her boss, Joe Biden, saw it. Weeks later, it was Sanders who told Biden about the explosive video of a police officer kneeling on George Floyd’s neck.

“Again?” Biden asked in disbelief. Sanders responded, she recalled in an interview, “Again. Again. This literally just happened again.”

The brutal 8-minute, 46-second video touched off a national reckoning and demonstrations across the country. And it threw Sanders, 30, into a unique, high-pressure role as the highest-profile African American staffer in Biden’s inner circle, tapped to explain — or justify — his record on race to sometimes-skeptical black activists even while advising him privately on how to navigate the moment.

The campaign deploys her to marquee shows like “Fox News Sunday” to make the case for Biden. She has been dispatched to reassure voters when Biden makes tone-deaf comments. Internally, she advises Biden on a wide range of issues, including his response when a crisis erupts in the country’s rapidly shifting racial justice landscape.

But as a bridge between Biden and black activists, Sanders sometimes finds herself taking shots from all sides. Biden, after all, is trying to harness the energy from the massive street protests while rejecting the protesters’ most visible demands, such as defunding the police.

Some civil rights leaders grumble that Sanders hasn’t done much to get Biden to meet the moment. Aimee Allison, founder of She the People, which advocates for minority women in politics, has criticized Biden for not reaching out enough to voters of color.

“You have millions and millions of people — some who supported other candidates in a large primary, and others who have been protesting in the streets — and the general sentiment amongst Democrats is for transformational change,” Allison said. “The moment doesn’t call for a justification. It requires us to move into a new phase.”

But if outsiders want Sanders to be more of an agitator, insiders sometimes want her to be less of one.

“If there’s a place where I think sometimes she still is learning, it’s that her role now is not to be a full-time activist,” said Rep. Cedric L. Richmond (D-La.), a Biden ally who closely coordinates with the campaign. “It is to figure out a pathway to accomplish the goals within the system. Sometimes I remind her that you can’t govern if you can’t win.”

Yet Sanders’s fans say she’s been indispensable to the presumptive nominee. She reached out to Floyd’s lawyer to determine how Biden could best offer his condolences after his death — and sobbed as she listened in on Biden’s call to the family.

She has briefed the Congressional Black Caucus at delicate moments, including as Biden denied an accusation of sexual assault by former Senate staffer Tara Reade, according to participants in that conversation. She sits on Biden’s criminal justice task force, which is developing his policies on the volatile issue.

Sanders has pushed the campaign to be wary of language that frustrates black activists, for example urging staffers to avoid the term “white working class,” according to a person familiar with the discussions.

“She’s in every meeting,” Richmond said. “There are not any decisions being made behind her back. She’s in the room. She participates with decisions.”

And Sanders’s role as an African American validator will only become more important as the Trump campaign ramps up its effort to use Biden’s sometimes tone-deaf comments on race to peel off some of his support from black voters.

For now, Sanders is offering advice as Biden makes the most important decision of his campaign: whom to choose as his running mate. She helped orchestrate a conversation between Biden and prominent black women pushing him to choose an African American running mate, according to two people on the call who spoke on the condition of anonymity to discuss internal campaign dynamics.

“I’m privileged to say I’ve been let into the circle to do this work,” Sanders said.

Breaking into Biden’s inner circle was never straightforward. When Sanders joined the campaign in spring 2019 as a senior adviser, she drew sharp criticism from liberal activists baffled that a young, outspoken black woman, and a former top aide to Sen. Bernie Sanders (I-Vt.), would lend her voice and charisma to a centrist Democratic politician.

It was no easier inside the campaign. Sanders quickly discovered that she was excluded from the daily 8:30 a.m. phone call among Biden’s top strategists, where major decisions were often made.

Of his senior aides, Sanders was by far the youngest — born two years after Biden abandoned the first of his three presidential campaigns — as well as the only one new to Biden’s orbit and the only African American. Sanders complained to Anita Dunn, one of Biden’s top aides and close confidantes, and Dunn immediately added her to the daily call.

Now the campaign frames that incident as evidence of Sanders’s value. “It was a perfect example of why you want somebody like Symone on the campaign,” Dunn said. “She didn’t wait to be invited.”

But the balancing act never ends. Sanders has developed ways of deflecting questions about whether she embraces Biden’s views, for example. “He might not get it right 110 percent of the time,” Sanders said at a recent event, deploying a straw man she often uses — after all, no one can be expected to agree 110 percent of the time, and that avoids the issue of just how much she does differ with her boss.

“It is my job to advocate for and protect his position,” Sanders said in the interview. “It is my job to communicate his position to other folks and explain to them why his position is actually the best position if we want to beat Donald Trump.”

Clearly that’s not satisfactory to many liberal black leaders, four of whom declined to discuss her on the record for this article. Several cited recent Biden senior hires who are black, saying they’d become more familiar with Karine Jean-Pierre and Ashley Allison, who have broad portfolios that include reaching out to black voters.

Rashad Robinson, executive director of the Color of Change Coalition, a racial justice group, told Vogue magazine in April, “I have not felt the effects of Symone’s presence. It has not translated for us.”

Internally, Sanders has developed tools to be sure she’s taken seriously. When overruled on a key decision, she makes a point of acknowledging that her idea is not carrying the day — but restates her position nonetheless, to ensure it does not get lost.

“It’s helpful because sometimes conversations start in one place and then go off in other directions,” Dunn said. “And sometimes it has the effect of bringing people back to what the core issue is. And sometimes it is just, Symone has made her position clear.”

The aftermath of Floyd’s killing showcased Sanders’s role. When she’d been an aide to Bernie Sanders in 2016, she would seek out civil rights attorney Ben Crump to hash through racial justice issues, even though he was firmly supporting Hillary Clinton, and they became friends.

So when Floyd died, the Biden team agreed Sanders should reach out to Crump, now an attorney for the Floyd family, to determine whether a call from the former vice president would be welcome.

“Do you think it’s the right time?” Sanders asked Crump, he recalled in an interview. He added, “She wanted to make sure she didn’t have the vice president just call for the sake of saying, ‘I called.’ ”

They had a robust discussion about how Biden should approach the family, and Crump said her efforts secured a “very dignified, a very engaging moment” for both Biden and Floyd’s family. In interviews later, family members praised Biden’s approach and contrasted it with President Trump’s.

“Vice President Biden, I loved his conversation,” Philonise Floyd, George Floyd’s brother, told CNN. “He talked to me for 10 or 15 minutes. And I was trying to talk his ear off. . . . But Trump? It lasted probably two minutes.”

Despite her activist aura, Sanders has always sought a role in mainstream politics, and her rapid rise follows a steep arc more typically seen from white men in Washington, though she comes from Omaha, with no family connection to politics.

As a student and leader at a local nonprofit, Sanders introduced former president Bill Clinton at a fundraising luncheon by age 16. She became Bernie Sanders’s presidential campaign spokeswoman by 25. She became a paid commentator on CNN and was granted an at-large seat in the Democratic National Committee by 26. She had a book deal by 28.

And this year, at 30, in addition to being a senior staff member to the presumptive Democratic nominee, she released her book, which is titled “No, You Shut Up: Speaking Truth to Power and Reclaiming America,” a rallying cry for young women trying to navigate politics based on her own experiences. (The book, Sanders said, was largely written before she started working on the campaign.)

A virtual party to celebrate the book’s launch last month was hosted by a quartet of female power brokers: Barack Obama confidant Valerie Jarrett, Democratic operative Hilary Rosen, Recode co-founder Kara Swisher and Washington fixer Tammy Haddad. Sen. Elizabeth Warren (D-Mass.), who joined as a special guest, swooned over Sanders’s book, which she said she had listened to in an audio format.

“This book is Symone at her funniest, her most outrageous and, ultimately, her most passionate,” Warren said.

During the event, Sanders described her broad goal thusly: “I want to be a powerful person.” She added, “Why? Because powerful people can help change things.”

Sanders vaulted into national politics in 2015, when Bernie Sanders, then a long-shot presidential candidate, needed to bulk up his communications operation and wanted help navigating the Black Lives Matter movement. Symone Sanders took on the role she is now reprising for Biden — helping an older white candidate understand the views of energized black activists, some of whom had begun disrupting events held by the presidential hopeful.

At an August 2015 rally with 28,000 people in Portland, Ore., Sanders went onstage to warn the crowd that the candidate might be interrupted by hecklers, and she led them in a chant they could take up in response: “We! Stand! Together!”

Jeff Weaver, then Sen. Sanders’s campaign manager, said she was a natural before a big audience. “Some people are all well and good about getting out to a crowd of thousands of people — then they kind of freeze,” Weaver said. “She had no problem.”

By late 2018, as this year’s vast Democratic presidential primary field was starting to take shape, it was clear that the party’s progressive flank was ascendant, and that Symone Sanders, by then a visible liberal spokeswoman, would be in great demand. She met with top-tier candidates like Warren and Sens. Kamala D. Harris (D-Calif.) and Cory Booker (D-N.J.).

She also traveled to Delaware to talk with Biden, whom she had never met, and the pair clicked. The interview, scheduled for 30 minutes, lasted two hours, and Sanders said she was the one to end it. “I said, ‘Oh, I’ve got a plane to catch. Sir, I’ve got to go,’ ” she recounted at her book party.

When she signed up with Biden, she became an immediate target. “I took a lot of flak for that decision,” Sanders said at her book party. “People questioned my character. They questioned my commitment to my values. They questioned if I even had political instincts.”

Sanders acknowledges she has not always met the challenge deftly, for example flubbing an early question from a reporter about the 1994 crime bill Biden authored, which critics say contributed to the mass incarceration of young black men.

But she has steadily pushed ahead, helping a man who came of age 60 years ago navigate the tricky terrain of 2020.

When Booker and Harris criticized Biden in 2019 for bragging at a fundraiser about his once-close relationship with segregationist senators, she was there to defend him. “The vice president did not embrace segregationists,” Sanders told CNN.

She was there again at a Democratic debate that year, when Harris called out Biden for his opposition to busing black children to predominantly white schools. Sanders said Biden’s more recent record as Obama’s vice president “is more indicative of what he believes now, the kind of president he will be, how he will govern, than something he said or did 40 years ago.”

And as Biden’s campaign appeared to be crashing after poor finishes in Iowa and New Hampshire, Sanders was dispatched to South Carolina, where Biden mounted a successful last stand based largely on his appeal to black voters.

Now that Biden’s campaign is conducted largely via virtual events, Sanders is more frequently seen on TV as a surrogate than physically at Biden’s side. Yet evidence of her presence abounds.

Last month, after a Biden “virtual roundtable” with big city mayors, Biden’s team failed to cut the audio feed when the event ended.

Though the screen was dark, Biden could be heard seeking her input. “You know, Symone, I think . . .” he said. And then the sound was cut.