Fourteen members of Congress have signed a letter demanding the release of Columbia University student Mahmoud Khalil, who was detained by Immigration and Customs Enforcement last week, despite being a legal permanent resident.

Khalil was detained on Saturday after two plainclothes Department of Homeland Security agents entered Columbia student housing and detained Khalil without presenting a warrant or any filed charges, according to the letter.

Khalil is a legal permanent resident and is married to a U.S. citizen who is eight months pregnant, according to the letter.

The 14 members of Congress — including “Squad” members Reps. Rashida Tlaib, D-Mich.; Ilhan Omar, D-Minn.; and Ayanna Pressley, D-Mass. — called Khalil’s detention an “attempt to criminalize political protest” and a “direct assault on freedom of speech.”

“Khalil has not been charged or convicted of any crime. As the Trump Administration proudly admits, he was targeted solely for his activism and organizing as a student leader and negotiator for the Gaza Solidarity Encampment on Columbia University’s campus,” the members of Congress wrote in a letter addressed to Department of Homeland Security Secretary Kristi Noem.

The members of Congress, all Democrats, also called Khalil’s detention an act of “anti-Palestinian racism intended to silence the Palestine solidarity movement in this country.”

The ICE agents who arrested Khalil at his home first said that the State Department had revoked his student visa. After being informed by Khalil’s attorney that he was a permanent resident with a green card, the ICE agents said that his green card was being revoked instead, according to the letter.

The agents also threatened to arrest Khalil’s pregnant wife, according to the letter.

“DHS initially informed them he was being held in Elizabeth New Jersey, but his wife attempted to visit the facility on Sunday only to learn that he was not there. DHS refused to provide additional information on his location to his attorney or spouse,” the letter said.

Shortly after his arrest, Khalil was transferred to an ICE facility in central Louisiana.

“Khalil’s constitutional rights have been violated. He has been denied meaningful access to counsel and any visitation from his family. This is absolutely unacceptable — and illegal,” the letter said.

A federal judge has blocked Khalil’s removal while weighing a petition challenging his arrest.

The Trump administration said it has the authority to remove Khalil under the Immigration and Nationality Act.

“Under the Immigration and Nationality Act, the secretary of state has the right to revoke a green card or a visa for individuals who serve, or are adversarial to the foreign policy and the national security interests of the United States of America,” White House press secretary Karoline Leavitt said Tuesday. “Mahmoud Khalil was an individual who was given the privilege of coming to this country to study at one of our nation’s finest universities and colleges and he took advantage of that opportunity, of that privilege, by siding with terrorists, Hamas terrorists.”

Baher Azmy, one of Khalil’s lawyers, called his client’s alleged alignment with Hamas “false and preposterous.”

“Setting aside the false and preposterous premise that advocating on behalf of Palestinian human rights and to plead with public officials to stop an ongoing genocide constitutes alignment with Hamas, his speech is absolutely protected by the Constitution, and it should be chilling to everyone that the United States government could punish or try to deport someone because they disapprove of the speech they’re engaged in,” Azmy told ABC News on Monday.

Khalil completed his program at the university in December and expects to graduate in May, according to the habeas corpus petition filed by his lawyer.

Leavitt also said Tuesday that more arrests will come and added Columbia University is “refusing to help” DHS in identifying other individuals.

“I also know that Columbia University has been given the names of other individuals who have engaged in pro-Hamas activity and they are refusing to help DHS identify those individuals on campus,” Leavitt said.