EXCLUSIVE: Sen. Ted Cruz, R-Texas, on Sunday called on President Biden to open up media access to border facilities where unaccompanied migrant children are being held, after no reporters were allowed on a lawmakers' tour of a facility – and Cruz himself was challenged for taking pictures.

Cruz wrote to Biden after he and 18 other senators last week toured a migrant center in Donna, Texas, where they saw (and released the images) of children packed in "pods," as well as babies brought by human traffickers.

The Republicans linked the crisis to Biden’s moves to roll back Trump-era border protections.

READ THE LETTER IN ITS ENTIRETY

"We understand the heartbreaking tragedy unfolding at the border because we were there. We saw it," Cruz said in a letter obtained by Fox News. "But the American people are unable to see it because you remain intent on keeping the media from shining a light on your administration's failures."

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Cruz on Friday had described the situation in the facility in Donna, Texas, as "inhumane" and "wrong."

Biden’s administration has come under heavy criticism from both Republicans and journalists for its lack of access to facilities.

"I will commit to transparency, and – as soon as I am in a position to be able to implement what we are doing right now," Biden said Thursday at a press conference in response to questions on the matter.

"And one of the reasons I haven’t gone down ... is I don’t want to become the issue. I don’t want to be, you know, bringing all of the Secret Service and everybody with me to get in the way. So this is being set up, and you’ll have full access to everything once we get this thing moving," he said.

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A day later, Cruz said not a single one of the reporters who came down to the border with the congressional delegation were allowed access to the facility, where he says 4,200 migrants were packed into a facility designed for 250. 

"They could not show the American people cages after cages of little boys lying side-by-side, of little girls lying side-by-side, covered with reflective emergency blankets with virtually no space between them," he said in the letter to Biden. "They could not see the playpen of infants and toddlers brought here by human traffickers and then left alone. They could not see the row of children who, having just been crammed into the crowded cages, were now testing positive for COVID-19."

Similarly, they were not allowed access to a makeshift processing center under a bridge across the border, Cruz said. Even in the facility, Cruz relayed his account of how a "political appointee" jumped in front of his camera to stop him from taking pictures – video of which he posted online.

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"This is outrageous. The Trump administration allowed media into DHS facilities. So did the Obama administration, the Bush administration and the Clinton administration. But you want to hide what is going on," he said.

Cruz intends to tour the Kay Bailey Hutchinson Convention Center in Dallas on Monday, where migrant children are also being housed and is nearing capacity limits – and urged Biden to allow access to that facility as well.

"I again urge you to stop denying reality, confront the consequences of your policies, and allow the media access to these facilities," he said. "The media should be able to come with me on my tour of the KBH center to show the American people what is happening in this country."

The letter comes as Republicans continue to ramp up pressure on the administration for the growing numbers of migrants, particularly unaccompanied migrant children. There are currently more than 5,000 children in Customs and Border Protection (CBP) custody and more than 12,000 in Health and Human Services (HHS) custody.

Republicans have blamed moves by Biden to end Trump-era policies like the Migrant Protection Protocols (MPP) – which kept migrants in Mexico for their hearings – and limiting immigration enforcement priorities for encouraging the surge.

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Biden’s administration has denied that and has referred to the situation as a "challenge" rather than a crisis, while conceding the numbers are "overwhelming." But Biden has stood by his rollback of Trump policies.

"Rolling back the policies of 'Remain in Mexico,' sitting on the edge of the Rio Grande in a muddy circumstance with not enough to eat? I make no apologies for that," Biden said on Thursday. "I make no apologies for ending programs that did not exist before Trump became president that have an incredibly negative impact on the law – international law – as well as on human dignity. And so I make no apologies for that."