Both Democratic and Republican lawmakers keep getting denied access to tour facilities holding undocumented immigrant children who have been separated from their parents, causing some to speculate whether the federal government is shielding the living conditions there from public scrutiny.

Most recently, Democratic Rep. Mark DeSaulnier was turned away Sunday from visiting a center in his district in Pleasant Hill, California, after previously receiving permission to tour the facility from an official in the Health and Human Services Department.

“I am now being told that this is not the case, and being directed to tour one of several facilities in other parts of the country,” DeSaulnier wrote in a letter to the federal Office of Refugee Resettlement, a subsidiary agency of HHS, the San Francisco Chronicle reported.

DeSaulnier added that he is “concerned that the Administration is attempting to only show Members of Congress certain facilities that highlight the quality of care [the White House claims] all children in detention are receiving.”

He has requested that HHS reconsider his request to visit the facility.

Just a week earlier at the same shelter in Pleasant Hill, where 25 immigrant teenagers were living at that time, GOP Rep. Jeff Denham was turned away from a scheduled visit.

“We confirmed with both HHS and let our counterparts at the White House know that we were coming,” Denham told the security guard who denied him entry, a local ABC affiliate reported.

He, too, questioned the motives behind why he was barred from entering.

“If you’ve got nothing to hide, I’d think you would want not only members of Congress to see, who are actually trying to write new laws to fix the situation, but I’d think you’d want the media to know as well,” Denham said in an interview with the ABC affiliate. “We want to make sure safety comes first for these kids.”

The facility in Pleasant Hill is run by the nonprofit Southwest Key and is licensed by California regulators.

A spokesman for Southwest Key has said that visitors are approved by the Office of Refugee Resettlement, which falls under the HHS umbrella.

“We welcome any Member of Congress after they receive ORR approval,” the spokesman said.

Across the country, other lawmakers have run into similar problems with scheduled visits.

Last week, GOP Rep. Carlos Curbelo of Florida said he was “outraged” that he had been denied from visiting a center in his state after he had “followed ‘protocol’” from HHS.

Curbelo’s visit had been confirmed with local operators for more than a week, he said.

“All protocols to request, schedule & get clearance were followed, and yet last night was told by @HHSGov staff in Washington I would be refused entry,” Curbelo tweeted.

Tried to visit an #ImmigrantChildren shelter today. Visit had been confirmed with local operators for over a week. All protocols to request, schedule & get clearance were followed, and yet last night was told by @HHSGov staff in Washington I would be refused entry.

— Rep. Carlos Curbelo (@RepCurbelo) July 6, 2018

Was disappointed when this happened to colleagues last month & @HHSGov excuse was protocol. Outraged today given my office followed “protocol.” Will be supporting @DWStweets’ bill to require Members of Congress be granted access to these facilities upon our return to Washington.

— Rep. Carlos Curbelo (@RepCurbelo) July 6, 2018

Curbelo said he will vote in favor of a bill from Rep. Debbie Wasserman Schultz that would require HHS to allow members of Congress to access the immigrant temporary housing facilities.

Wasserman Schultz and Sen. Bill Nelson, both Florida Democrats, were “blocked” in June from entering a facility in Homestead, Florida, where more than 1,200 immigrant children are staying, including dozens who are separated from their parents.

The company that runs the facility had granted the lawmakers permission to tour it, but HHS stepped in to prevent that.

HHS also blocked Oregon Sen. Jeff Merkley and five other people from visiting a center in Texas in June. The department has said that Merkley and his cohort showed up unannounced.

“Thankfully for the safety, security and dignity of the children being cared for there, they were denied access,” a spokesperson for HHS’ Administration for Children and Families told ABC News. “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.”

On Saturday, the Trump administration handed over a list of names of undocumented immigrant children under 5 years old who were separated from their parents at the border, in compliance with a federal court order.

At least 19 parents of children in custody have already been deported, a Justice Department attorney testified in court Friday, CNN reported.

The administration has asked for an extension to the Tuesday deadline to reunite families, citing logistical hurdles.