The glitzy Oprah Winfrey–hosted “Unite for America” Zoom event Sept. 19 featured the corps d’elite of entertainment, government, and business, as well as the woman being feted herself: Democratic presidential nominee Kamala Harris.

The event brought together the 140 “unity groups” that have held Zoom calls to fundraise for Harris, including White Women: Answer the Call, White Dudes for Harris, Cat Ladies for Harris, and Tech4Kamala.

“The grassroots people-powered movement behind Kamala Harris has unleashed a unifying force unlike anything we’ve seen in politics in a very long time,” Winfrey almost sung to the crowd. Then the media mogul pivoted to face a woman wearing a deep-violet dress in the front row: Jotaka Eaddy, who started this movement with her weekly Zoom call for powerful Black women.

“I know y’all been doing this a long time,” Winfrey told Eaddy. “I was on a lot of calls with y’all in 2020. But we ain’t never seen nothing like this before!”

That’s no understatement. Featuring stars from Tracee Ellis Ross to Chris Rock to Michigan Gov. Gretchen Whitmer, the YouTube livestreams of Winfrey’s event had more than 2 million views by the following afternoon. The event was also aired in part on CNN and MSNBC.

All this was more than Eaddy, a 45-year-old social impact consultant in politics and tech, could have dreamed of four years ago when she started her group, Win With Black Women (WWBW), while quarantining in her family home at the end of a dirt road in South Carolina.

The Sunday evening Zoom call has evolved into a potent under-the-radar network of influential Black female leaders pulling strings in American public life and business. Most weeks, the call draws a couple hundred attendees. But in the heady first few hours of Harris’s campaign on July 21, some 44,000 participants swamped Eaddy’s Zoom, with another 50,000 tuning in on other platforms. That call raised $1.6 million for the Harris campaign in one evening, and it set off a wave of Zoom gatherings that have raised many millions more, and made the teleconference platform such a valuable fundraising tool that some have dubbed 2024 the year of the “Zoom election.”

There’s nothing new about Black women leading the charge, Eaddy told Winfrey. “It was a moment in our country to show what Black women have always done,” she explained, invoking women of earlier generations who are not here to see one of their own on the path to the nation’s highest office.

“It is an honor for all of us to usher in this moment,” Eaddy continued, “knowing that those who watered this mighty field are now allowing us to eat of the fruit of the trees.”

Kamala Harris sits across from Oprah Winfrey at a "Unite for America" election rally.

A network with deep roots

The dizzying ascent of Win With Black Women into the political sphere isn’t serendipitous—at least not in the typical sense. Instead, it’s the culmination of years of planning, strategizing, and organizing to harness the financial and social capital of Black women. “It’s about using our collective economic power to demand that we’re given a seat at the table,” says Shannon Nash, the former CFO of the Alphabet subsidiary Wing. “And, more importantly, building our own table.”

WWBW has grown mainly from member introductions as an if-you-know-you-know grassroots movement. Meghan, Duchess of Sussex, attended the call in 2022 to discuss the press’s treatment of Black women. Winfrey likes to drop in. Other guests have included the singer Dionne Warwick, the late Hollywood star Cicely Tyson, and the filmmaker Ava DuVernay.

It’s a power-player-filled world far removed from Eaddy’s upbringing, in a “humble” home on an unpaved road in Johnsonville, S.C. She learned public speaking giving Easter speeches at church. In high school, her debating prowess won her a nomination to attend a conference for aspiring lawyers.

But at a cost of $3,000, her parents couldn’t afford to send her, Eaddy tells Fortune. That was the first time she saw the power of a network: “Black women in my church and in my community sold chicken dinners and held bake sales to raise money to send me to that conference and to put me on an airplane that many of them have still never been on,” recalls Eaddy.

At the University of South Carolina, she was the first Black woman to be elected student body president. She went on to work for a group seeking to abolish the death penalty. After stints at the NAACP and with then-Sen. Barack Obama’s presidential campaign, she headed to Silicon Valley, where she did civic engagement at tech startups.

In 2019, she launched the social impact consulting firm Full Circle Strategies, specializing in public affairs and community engagement. That remains her “day job,” even as WWBW has taken on a life of its own.

‘Put me in’

in August 2020, Joe Biden, then the presumptive Democratic presidential nominee, had said he was considering several Black women as his vice presidential pick. The names of then-Senator Harris and the Georgia voting rights activist Stacey Abrams were floated in the media, which opened them up to “abominable sexist and racist attacks,” Eaddy says.

“I just remember thinking to myself, If we allow this to happen to these Black women, then what is happening to Black women that don’t have those platforms, that aren’t famous, [and] are not at a level of vice presidential nominee potential?” Eaddy says. “What is happening to the ‘Tamikas’ in the workplace?”

Eaddy called Minyon Moore, a former White House political director and more recently the chair of the 2024 Democratic National Convention, to ask what was being done to address the abuse and how she could assist.

“Put me in,” she recalls telling Moore, and explains: “You always wait for the political aunties to lead you.”

But Moore turned the question around on Eaddy: “What are you all planning to do?” she asked. Half an hour after ending the call, Eaddy sent out an email to her network that was part rant, part call-to-action titled, “Not On Our Watch.”

That night, 90 Black women from a range of industries gathered on a Zoom call and drafted an open letter denouncing the attacks on VP candidates. “That was the very beginning of Win With Black Women,” says Eaddy.

Time to take center stage

On its Zoom calls, WWBW has hosted nearly every Black woman candidate running for a major office, including Harris herself. Says Eaddy: “On the spot, we will fundraise for those Black women.”

But politics isn’t the only arena where WWBW has flexed its power. “When there’s a need, we will galvanize,” Eaddy explains. And each participant brings her own assets.

“I’m a businessperson, and my lane is to help raise money, write checks, and strategize,” says former Amex executive Susan Chapman-Hughes, who sits on the boards of Toast and the J.M. Smucker Co. “The beauty of Win With Black Women is that people are like, ‘This is what I bring to the table in terms of skills and capabilities, and from there, we’re going to follow your lead—whatever it is you need.’ ”

After Disney released The Little Mermaid in 2023, featuring a Black Ariel and prompting a racist backlash, WWBW bought out over 100 theaters on opening weekend.

“It was important for us to support and to send Hollywood a signal that Black women are paying attention to the images that they create,” says Eaddy. The group has also rallied behind Black female authors to help get them on bestseller lists. And it has strategized to support Black female athletes.

“Black women have always been powerful, but behind the scenes, stage directing,” says Ulili Onovakpuri, a managing partner at Kapor Capital. “Now we’re saying, ‘No, we want to be center stage—the main character.’ ”

Oprah Winfrey, wearing white, holds hands with Jotaka Eaddy, Win With Black Women's founder, in purple. — Oprah Winfrey has made several visits to Jotaka Eaddy’s Win With Black Women Zoom call.

The group is in its element when going to battle on behalf of Black women facing seismic challenges—as Harris is now. The network was one of several hounding the Biden administration to negotiate for the release of WNBA player Brittney Griner from a Russian prison, penning an open letter, launching a social media blitz, and arranging meetings between Griner’s wife, Cherelle, and the Biden administration. Keisha Lance Bottoms, the former senior advisor to President Biden, describes Eaddy as “the woman who brought Brittney Griner home.” (Eaddy demurs, pointing out that the network’s efforts were part of a larger push.)

WWBW has often deployed this three-pronged strategy: a social media campaign; open letters to policymakers and government officials; and tapping well-connected insiders to press the case in their respective fields.

After Biden nominated Ketanji Brown Jackson to the Supreme Court in February 2022, the network mobilized to fight attempts to discredit her. It offered press training to Black women deans and professors at law schools to help them articulate Jackson’s legal chops. Members called their senators and attended Jackson’s in-person confirmation hearings.

“We wanted those senators to clearly see us,” says Eaddy. “And to see that if they chose to ask some of the ugly questions that they did, contort her record, or misrepresent the truth, we were ready to push back and make clear her qualifications.” On June 30, 2022, Jackson became the first Black woman to serve on the nation’s highest court.

Similarly, WWBW mobilized behind the economist Lisa Cook when she was nominated to the Federal Reserve’s Board of Governors, launching a splashy social media campaign and calling lawmakers. On May 10, 2022, Cook became the first Black woman to sit on the Federal Reserve Board in its 110-year history.

The evening that it all came together

On the July afternoon when Biden withdrew from the 2024 election and backed Harris, Eaddy told Winfrey, “We wanted to gather in our joy—and we knew that we needed to get to work.”’

That afternoon, Eaddy’s group chat with Black women leaders began “popping off,” she recalls. “We were like, ‘Okay, this thing is going down. We can’t believe this is happening.’ ” On a typical Sunday, about 200 women attend the 8:30 p.m. Zoom meeting. But by 5 p.m., a few hundred were already in the waiting room.

As the evening wore on, Eaddy’s phone was flooded. “I had about 600 missed calls that night from people asking how to get on the evening call.”

By 8 p.m., Nash and several other regular attendees were unable to join the Zoom. Even Eaddy was locked out. “This person had told this person who had told that person,” Nash says. “Someone had to put their phone on speaker for me to tune in.”

Eaddy switched to a Zoom webinar, which allowed for up to 3,000 participants. “We hit 3,000 immediately,” she says. At around 9 p.m., a member with a connection at Zoom reached out to higher-ups to expand their dial-in capacity to 50,000.

An hour into the call, television personality and attorney Star Jones created a fundraising link to funnel donations directly to the Harris Victory Fund. WWBW has so far raised $2.6 million for the cause.

It’s a wondrous thing, says Eaddy: “We’re seeing Black women leaning into their power—and we’re like the Avengers coming together.”

This article appears in the October/November 2024 issue of Fortune with the headline “How a weekly Zoom call of powerful Black women created the most potent campaign tool of 2024.”

More from the October/November issue of Fortune:
–See who made the 2024 Fortune Most Powerful Women list
–Cathy Engelbert is leading the WNBA to historic highs. Critics wonder if she’s fully seizing the moment
–Should you start a company with your friend?
–How GM CEO Mary Barra is transforming the auto giant for the EV future

How an under-the-radar network of powerful Black women created the most potent campaign tool of 2024 and raised millions