Rep. Ayanna Pressley announced on Wednesday that she is endorsing Sen. Elizabeth Warren for president.

It’s a departure from Reps. Alexandria Ocasio-Cortez, Ilhan Omar, and Rashida Tlaib, fellow progressive members of Congress with whom Pressley is often associated, but who are backing Sen. Bernie Sanders.

“At a time when so many people find their lives threatened and their dreams denied, we need bold, compassionate leaders who put power back in the hands of people,” Pressley, a Democrat from Massachusetts, said in a statement to media on Wednesday. “We find ourselves in a fight for the soul of our nation, and I know Elizabeth can win it.”

Reps. Ocasio-Cortez and Omar had endorsed Sanders in mid-October, with Tlaib officially joining them later that month.

The four first-term congresswomen are often called “the Squad” by admirers and critics alike, but there are plenty of differences among the women. Pressley’s decision to break with her fellow members of Congress is a reminder that the Squad isn’t a monolith.

“Ayanna has tremendous respect for her sisters-in-service,” a spokesperson for Rep. Ayanna Pressley (D-MA) told Vox in October. But “ultimately, these political decisions are made as individuals.”

Pressley’s endorsement breaks with Reps. Ocasio-Cortez, Omar, and Tlaib

Pressley announced her endorsement on Wednesday with a statement and video. Warren is “fighting for fundamental change that restores power to those who’ve been left behind and centers those who’ve never had access to it in the first place,” the congresswoman says in the video. “I’m proud to call her my senator. I can’t wait to call her our president.”

The endorsement is a major one for Warren’s campaign — perhaps the most high-profile yet, according to Astead Herndon of the New York Times. A progressive seen as popular with younger voters, Pressley will also, as Herndon notes, serve as a prominent black voice in a campaign that still trails former Vice President Joe Biden among black voters.

Pressley will appear with Warren at a town hall on Thursday in North Carolina, one of six battleground states where a recent New York Times/Siena College poll showed President Trump beating Warren (unlike in other battleground states polled, Trump also beat Biden in North Carolina).

In choosing to endorse the senator from Massachusetts, Pressley was making a break with some of her closest allies in Congress, who have endorsed Sanders.

The endorsement of Sanders by Ocasio-Cortez and Omar was first reported by the Washington Post on October 15. Omar officially announced her endorsement on Twitter, while Ocasio-Cortez was reportedly waiting for an event later that week.

Omar’s tweet included Tlaib, but that day, CNN reported that Tlaib had not, in fact, officially endorsed Sanders.

Spox for Tlaib says Sanders will come visit later this month, but she has not made a decision to endorse. https://t.co/HiaYUG57HH pic.twitter.com/sGL4E5WaJx — Greg Krieg (@GregJKrieg) October 16, 2019

“I have not made any endorsement at this time,” Tlaib said in a statement to CNN on October 16. However, later in October, Tlaib officially joined her fellow members of Congress in endorsing Sanders.

“I am endorsing Amo Bernie Sanders because he’s not gonna sell us out,” Tlaib said in a video released on Sunday, according to CNN. “He understands that it’s not just about policies and about words, but it’s going to be also about completely transforming the structures in place.”

The video was posted just after Tlaib spoke with Sanders at a rally in Detroit. “We deserve someone who writes the damn bills,” Tlaib said at the rally, CNN reports. “We deserve Bernie Sanders.”

The endorsement by Ocasio-Cortez and Omar earlier this month was important, Vox’s Sean Collins explained, because it gave Sanders a boost at a time when he had been dropping in the polls and was returning to the campaign trail after a heart attack.

Pressley’s break with her colleagues isn’t unprecendented

Ocasio-Cortez, Omar, Tlaib, and Pressley have been closely watched as the 2020 election cycle gets under way because they are politically influential, both together and on their own. The four are often referred to as the Squad, a name that started with a 2018 Instagram post by Ocasio-Cortez.

But the congresswomen have maintained that while media outlets, fans, and critics alike now refer to the four of them as the Squad, they don’t necessarily think of themselves that way.

“Our squad is big,” Pressley said at a press conference earlier this year. “Our squad includes any person committed to creating a more equitable and just world.”

“We are more than four people. We ran on a mandate to advocate for and to represent those ignored, left out, and left behind. Our squad is big. Our squad includes any person committed to creating a more equitable and just world.” -@AyannaPressley pic.twitter.com/gBtzatOjWS — Justice Democrats (@justicedems) July 15, 2019

And there are plenty of differences among the four women. Pressley, in particular, began her career working for mainstream Democrats like John Kerry, as Joanna Weiss reported at Politico earlier this year. She’s also broken with Tlaib, Omar, and Ocasio-Cortez before, voting in favor of a House resolution opposing the Boycott, Divestment and Sanctions movement, an economic protest of Israeli policy, while her three colleagues voted against it.

And Pressley’s history in Massachusetts, where Warren is the senator, also likely comes into play in her endorsement. As Herndon notes, Pressley won a primary bid against incumbent Democrat Michael E. Capuano to become the first black woman elected to Congress from Massachusetts in 2018. At the time, Warren declined to endorse Capuano over Pressley, even though he was the party incumbent. “Now,” Herndon writes, “it’s Ms. Pressley playing power broker, as Ms. Warren seeks to usurp the establishment herself.”

Meanwhile, the fact that Pressley is breaking with her colleagues is a reminder that the Squad, while a powerful symbol for many voters (as well as a favorite object of vitriol for President Trump and others on the right), was never meant to be a voting bloc. As Pressley notes, the four congresswomen are individuals. Each will presumably make her own decisions about how to use her political power in 2020 and beyond.