Sen. Jeff Merkley said his attempt over the weekend to get into a U.S. facility for housing child refugees started when he read news coverage about the policy of separating children from parents at the border.

“When I read about this, I found it almost unbelievable. It’s just — really?” Merkley said in a phone interview with TIME. “Are we really putting children through a traumatic experience here in the U.S. in order to dissuade their parents from seeking asylum?”

On Sunday, the Oregon Democrat attempted to enter a facility in Texas where he says unaccompanied children, including some who were separated from their parents, are being held.

He describes the facility as a large, windowless building that used to house a Wal-Mart, but now has “1,000 children locked up inside.” When he approached the door of the facility, the Senator’s entry was denied. Merkley shared a now-viral video of his attempts to enter, and subsequent interactions with the facility’s supervisors, on social media.

The Senator says he wanted to tour the facility to see what was happening for himself and to call attention to family separations, which he says are part of an administration effort to dehumanize people seeking asylum in the U.S. “A part of this is the dehumanization of people seeking asylum in this U.S.,” he says.

The separations are happening under a “zero tolerance” policy at the border that Attorney General Jeff Sessions announced earlier this spring. Under the policy, any person caught illegally crossing the border will be prosecuted and, as a result, parents who cross the border with their children are separated from them. Parents are handed over to the U.S. Marshals Service while the children are placed in the custody of the Office of Refugee Resettlement, which is run by the Department of Health and Human Services. In early May, some 658 children were separated from their parents at the border.

Experts say it can be very difficult for the separated family members to reunite. The Trump Administration has suggested the policy would be a deterrent for those seeking to come into the U.S. illegally.

Going in, Merkley said knew he likely would not be able to access the facility, which is being run by Southwest Key Programs. Prior to the visit, the Senator’s office had reached out to the federal agency that is responsible for unaccompanied children when they enter the U.S. and told officials that he’d like to see the facility. The Senator says his staff was informed that the facility has a policy of not letting people enter, but that if they’d been given “extensive advanced warning” they could try to arrange something. There were no guarantees.

But the Senator went anyway. “I just don’t feel that any member of Congress should have to wait weeks or months to visit a facility to see what the hell is going on inside of it,” says Merkley. “They’re trying to wrap this in a blanket of secrecy.”

In a statement to TIME, a spokesperson for the Department of Health and Human Services’ Administration for Children and Families said that the Senator and five others attempted to enter the shelter “unannounced and broadcast live via social media last night in Texas” but were “thankfully” denied entry.

“The Department of Health and Human Services takes the legal mandate to care for these children seriously. No one who arrives unannounced at one of our shelters demanding access to the children in our care will be permitted, even those claiming to be U.S. Senators,” the statement reads. “Senator Merkley should respect the UAC program and engage in the appropriate processes, as many of his colleagues have done before him, to visit ORR facilities. We would welcome him to engage in that process so that he may visit the facility to make headway on this important issue, rather than just headlines.”

According to the ACF website, requests to visit facilities are subject to evaluation before being granted.At least two weeks prior notice is required, though some requests may be granted if there are “exigent circumstances.”

Michelle Brané, the Director of the Migrant Rights and Justice program at the Women’s Refugee Commission, says her organization has been monitoring and advocating for oversight of Office of Refugee Resettlement facilities for a long time. Brané, who has worked on immigration and human rights related issues for over two decades, says while she thinks there are aspects of the process that need to be improved, visits to ORR facilities should be “done in a way that is thoughtful and that takes into consideration the protection needs of this population,” which can include very young children.

“Absolutely elected officials, especially those who have a say in how our policies are being implemented, should be able to conduct oversight, but the devil is going to be in the details,” she says. “There’s got to be some process for the facilities and the agencies running the facilities to be able to create the protections necessary for the kids.”

She adds, “The real issue right now is why they’re being separated in the first place.”

Merkley sits firmly among the critics of the administration’s “zero tolerance” approach, which he called “cruel” and “terrible” in the interview with TIME. In addition to visiting the ORR facility, the Oregon Democrat toured a border processing center in McAllen, Texas, and a respite center run by the Sacred Heart Catholic Church. At the processing facility, Merkley says he saw people jammed into cages that resembled dog kennels, sleeping on floors with only “space blankets” to keep them warm. He described what he witnessed as “disturbing.”

In a statement, a Department of Homeland Security press secretary said: “We appreciate the Senator’s interest in the subject, and are happy to provide him with an understanding of the immigration process: DHS follows the laws passed by Congress and processes alien children safely and humanely. Contrary to any misinformation campaign, the safety of children is paramount for DHS. The administration has worked tirelessly to educate members on what steps need to be taken legislatively to secure our borders and curb illegal immigration and will continue to do so. I encourage Senator Merkley to work with the administration to fix the underlying loopholes that act as a pull factor for illegal immigration and place these children at risk from smugglers and human traffickers.”

The statement continued, “At 2pm on a Friday, the Senator asked to visit a secure DHS facility over the weekend where children are present and we worked with him to provide him access. This presented obvious and serious privacy concerns – not to mention disrupting operations. He was able to visit the facility on Sunday.”

“The whole idea of injuring children as a deterrent for those seeking asylum is completely out of character with the soul of America, a nation where the vast bulk of us are from immigrant histories,” says Sen. Merkley, adding that the U.S. has a responsibility to provide asylum to those who seek it. “This is not zero tolerance. It’s zero-humanity. It’s wrong. It must be opposed. It needs to be changed immediately.”

The Senator says he plans to develop legislation to address the policy and call on the appropriate committees to take action. “If the committees don’t take action I want to explore whether or not we should have a shadow hearing,” he says.

Correction: The original version of this story incorrectly attributed a Department of Homeland Security statement. It was Tyler Houlton, not Katie Waldman, who issued the statement.

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