Fortune’s Most Powerful Women Summit has lost another high-profile guest: Brandi Carlile announced Monday that she won’t participate in the money mag’s summit, which begins today in Washington, D.C.

Carlile, who was slated to perform Tuesday, is withdrawing because former Homeland Security Secretary Kirstjen Nielsen is one of the scheduled speakers. While Nielsen resigned in April, she oversaw President Donald Trump’s immigration policy that separated thousands of migrant families at the border.

“Dropping out of such a special appearance is rarely my style,” Carlile wrote on social media, after opening her statement with a lyric from “The Joke.” “I believe in showing up and lending my voice. Joining the power. However, I don’t think human rights violators and merit-based abusers of displaced people should be given a platform to ‘reimagine’ history. Ever. The atrocity of family separation at our Southern border needs to go down in history as one of the United States of America’s most merciless acts.”

Carlile becomes the latest guest to back out of Fortune’s three-day conference that convenes prominent women in business, government, the nonprofit sector, education and the arts, such as former National Security Adviser Susan Rice, Best Buy CEO Corie Berry and U.S. Sen. Martha McSally, R-Arizona. As activists have called on Fortune to pull its invitation to Nielsen, Hillary Clinton and filmmaker dream hampton have canceled their appearances. While Clinton’s camp formally chalked the decision up to a scheduling conflict, an unnamed source told the Huffington Post that Nielsen’s participation was the real reason.

Carlile is no stranger to lending her voice to causes she supports. Last year the hometown folk rocker performed during Seattle’s March for Our Lives and is currently challenging country radio’s gender disparity with her all-star, women-led band the Highwomen.

“Respectfully, I absolutely cannot support Kirstjen Nielsen having a voice among the most powerful and inspiring women in America,” Carlile said in her statement, which you can read below in full. “Her access to power is righteously over. I forgive her. I mean no disrespect. I wish her well and hope that she comes to understand the error in her part of this shameful policy.”