EXCLUSIVEArizona Attorney General Mark Brnovich is inviting Health and Human Services (HHS) Secretary Xavier Becerra on a tour of the Southwest border, saying the conditions amid the surging crisis constitute a "clear threat" to the health of migrants and Americans.

"I write with a crucial invitation for you to join me for a tour of the southwest border in Arizona, at your earlier availability," Brnovich wrote to Becerra in a letter obtained by Fox News. "There can be no doubt that the conditions here now constitute a clear threat to the health of Arizonans, Americans and the thousands of undocumented immigrants that are entering our country with each passing day."

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The Biden has been facing a crisis at the border, and a surge in migrants that has outpaced anything in recent memory -- with more than 172,000 migrant encounters in the month of March. 

While Customs and Border Protection (CBP) has been at the forefront of the crisis, HHS has also played an important role due to the dramatic increase of unaccompanied child migrants -- who will end up in the care of HHS.

The agency has been quickly opening facilities along the border to handle the influx of minors, while also reducing COVID-era capacity limits. While single adults and some migrant families are being returned via Trump-era Title 42 health protections, the Biden administration is not applying that to unaccompanied children.

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Images of migrants packed in overcrowded facilities have drawn widespread criticism, although the Biden administration has sought to blame the Trump administration for not doing enough to prepare for the surge. Republicans have said the liberalization of border and immigration policy under President Biden have encouraged migrants to make the journey north.

In his letter, Brnovich says the images in facilities "appears contrary to all of the precautions that we have been told are necessary to prevent the spread of the deadly pandemic."

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"My sincere hope is that together we can review what is actually transpiring at the border, speak with the people on the frontlines, and that [HHS] can help ensure that Arizona is doing everything possible to protect the well-being of Americans as well as undocumented immigrants," he writes.

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The letter comes after Brnovich wrote to Vice President Kamala Harris earlier in the week, inviting her on a similar tour of the border for a "firsthand" look at the crisis.

Harris was made Biden’s point person to address "root causes" of the crisis, but has so far not visited the border. The White House has said she is engaged in "high level diplomatic work" to solve the crisis.