Another high-profile headliner has dropped out of Fortune’s Most Powerful Women Summit in protest of Kirstjen Nielsen, the former homeland security secretary who is scheduled to speak at the prestigious event.

Prominent speakers like Hillary Clinton and filmmaker dream hampton have fled the summit’s lineup in recent days, citing Nielsen’s participation in the Trump administration’s zero-tolerance immigration policy that resulted in thousands of children being separated from their parents at the border.

Singer Brandi Carlile became the latest celebrity to drop out in protest, as pressure mounted on remaining headliners like Rep. Tulsi Gabbard and Anita Hill to take a stand.

“At the end of the day I’m a mother with a ridiculous birthright and a heart for displaced people,” Carlile wrote in a statement on Twitter. “Respectfully, I absolutely cannot support Kirstjen Nielsen having a voice among the most powerful and inspiring women in America.”

Clinton announced last week that she would no longer be speaking, citing scheduling conflicts. But a person close to the former secretary of state told Slate she cancelled after learning Nielsen was part of the lineup. Hampton cited Nielsen’s “immoral and reprehensible actions” when she pulled out last week.

More than 53,000 people have signed onto a petition asking Fortune to disinvite Nielsen from the yearly event, which brings together the most prominent women in the Fortune 500. In a statement, Fortune spokeswoman Alison Klooster said the organization wanted Nielsen to have to answer “tough questions” in a “no-holds-barred interview.”

“We believe that the most powerful women in business, who also happen to be some of the most powerful women in the world, have strong views about how the U.S. Administration has handled its immigration policy,” Klooster said. “We sought out an opportunity to bring the woman who was effectively responsible for that policy to ask her tough questions publicly and on stage about that policy.”

Nielsen will appear in a 30-minute segment on Tuesday called “The Hard Questions,” moderated by PBS NewsHour’s Amna Nawaz. She was previously scheduled to speak on a panel with Cisco Chief Security Officer Edna Conway, focused on Neilsen’s time at the department and the border security landscape. Klooster told the Huffington Post that the panel description changed because Conway was no longer able to attend.

Gabbard, a Democratic presidential candidate who sparred with Clinton on Twitter earlier this week, is still scheduled to speak at the summit during dinner program on Tuesday night. And Hill, the law professor who became a feminist icon after testifying against Supreme Court Justice Clarence Thomas, will speak at a segment on the future of the #MeToo movement.

Both women, along with actress Eva Longoria and former U.N. Ambassador Susan Rice, have been pressured on Twitter to drop out of the program. Even journalists who planned to cover the summit received pushback from concerned citizens, many of whom used the hashtag #NoSoftLanding—the same slogan activists used to protest Nielsen’s inclusion in the Atlantic Festival last month. (The Atlantic announced a week before the festival that Nielsen would no longer be able to attend.)

Amy Nelson, the founder of women’s coworking space The Riveter, responded to the public pressure in a lengthy Twitter thread in which she said she had considered dropping out of the summit, as well. Instead, the lawyer said, she decided to attend in order to ask Nielsen about her role in family separations.

“Like it or not—and I don’t—the Trump administration and his executives are powerful beyond words,” she tweeted. “@SecNielsen is part of that power. Her actions will live on in history. In infamy. We must ask her why.”

As Homeland Security secretary, Nielsen oversaw the implementation of the zero-tolerance policy starting in June 2018. According to the ACLU, more than 2,000 children were separated from their parents at the border as a result of Trump administration policies and more than 100 have yet to be returned.

Last summer, Nielsen famously claimed the administration did not have a policy of separating families at the border—a claim the Washington Post fact checker dismissed as “Orwellian.” She resigned as secretary in April of this year.