Kamala Harris is counting on her sorority sisters

There are many glass ceilings a Kamala Harris presidency could shatter. One of them is that she could be the first black sorority member to sit in the Oval Office.

The US vice-president, who spoke on Wednesday at the biennial convention of Zeta Phi Beta, is a life-time member of Alpha Kappa Alpha.

The two organisations are among the predominantly black sororities and fraternities that make up the National Pan-Hellenic Council.

Commonly called the Divine Nine, its nearly four million members are poised to become a secret weapon as Ms Harris seeks the presidency.

The US vice-president is a member of the nation's oldest historically black sorority

Less than 24 hours after Joe Biden endorsed his deputy to seek the Democratic nomination in his place, the group vowed to launch an "unprecedented voter registration, education and mobilisation" drive.

As a non-profit, the National Pan-Hellenic Council is non-partisan and cannot officially endorse Ms Harris.

But it is promising a campaign that "will activate the thousands of chapters and members in our respective organisations to ensure strong voter turnout in the communities we serve".

That is in line with how the Divine Nine historically gets behind its own. Its members have supported Ms Harris, 59, in the past as she climbed the ladder of national politics.

Members of Zeta Phi Beta, part of the Divine Nine, applauded Ms Harris on Wednesday.

Greek life on US university campuses typically evokes images of young white men or women living together in group houses and drinking booze out of red solo cups.

But black Greek-letter clubs emerged at the turn of the 20th century as support systems that offered kinship to black students experiencing segregation and social isolation at majority-white institutions.

The first black fraternity, Alpha Phi Alpha, began as a study group at Cornell in 1906, according to The Divine Nine: The History of African American Fraternities and Sororities by Lawrence C Ross.

Its membership has included civil rights icon Martin Luther King Jr, former Supreme Court Justice Thurgood Marshall and Olympic gold medallist Jesse Owens.

Ms Harris pledged Alpha Kappa Alpha, the nation's oldest black sorority, as a senior - or fourth-year student - at Howard University in Washington DC.

She has previously said the experience "changed my life".

AKA members supported their sister in her short-lived 2019 presidential bid

Both in its individual parts and as a collective, the Divine Nine is built around shared values of scholarship, civic engagement and community service.

It has lobbied in the past for everything from federal anti-lynching legislation and women's suffrage to high school tutoring and financial aid opportunities for black youth, according to Mr Ross's book.

Membership is for life, he writes, which is "almost spiritual" and "makes you realise that your life on earth has more meaning than just your own selfish needs".

Of her AKA connection, Ms Harris said in 2019: "Throughout your life, you find friends who become family and – like family – they help shape you and your life experiences. For me, that was the women of Alpha Kappa Alpha Sorority, Inc. who became my sisters."

That year, as the then-California senator launched a campaign for president, her fellow "sorors" canvassed and phone-banked to get out the vote.

When she became Mr Biden's running mate, images of AKAs and other Divine Niners, accessorised with heels and pearls, went viral for their Stroll to the Polls in Atlanta, in the battleground state of Georgia. The Biden-Harris ticket went on to narrowly win the state, powered in part by strong black turnout.

VP Harris meets with the Divine Nine's council of presidents in 2021

Though Ms Harris's candidacy for the November 2024 election is only a few days old, the backing of her sisters is already providing consequential.

On a Sunday night Zoom call, the group Win With Black Women - which includes several Divine Nine members - helped raise more than $1m (£775,000) in roughly three hours for the nascent campaign.

"People are just energised," Crystal Sewell, an AKA leader, told CBS News, the BBC's US partner.

"And really really excited about possibilities [as] it relates to VP Harris and her candidacy."

Ms Harris, who is seeking to make history as America's first female president, is leaning into that enthusiasm.

Speaking to 6,000 fired up Zeta Phi Beta women at a convention centre in Indianapolis on Wednesday, she promised them "we are not playing around" if she defeats Donald Trump this November.

Her keynote address was scheduled weeks ago, but - touching on topics such as abortion, gun control and Project 2025 - the vice-president laid out the stakes of her candidacy.

"We face a choice between two different visions for our nation," she told the crowd. "One focused on the future, the other focused on the past. With your support, I am fighting for our nation's future."

"So let us continue to fight," she added, "because when we fight, we win."