Nine senators on Saturday sent a letter to the Biden administration condemning his handling of the influx of migrants coming to the U.S.-Mexico border and calling for more "clarity."

Senate Judiciary Committee Ranking Member Chuck Grassley, R-Iowa, led the letter signed by Republican committee members Sens. Marsha Blackburn, R-Tenn.; Thom Tillis, R-N.C.; Ted Cruz, R-Texas; Josh Hawley, R-Mo.; Mike Lee, R-Utah; Tom Cotton, R-Ark.; and John Kennedy, R-La.

"Regardless of what the Biden Administration wants to call this current set of circumstances it has created, this surge in illegal immigration carries significant risks," the senators wrote to Homeland Security Secretary Alejandro Mayorkas and Health and Human Services Secretary Xavier Becerra. "It also imposes a heavy burden on public resources."

Senator Chuck Grassley (R-IA) walks to a Republican caucus luncheon. (Photo by Sarah Silbiger/Getty Images)

The senators added that "Congress and the American people must have additional clarity about how DHS and HHS are addressing" the situation at the border.

There were 30,077 border apprehensions in February 2020. In February this year, Customs and Border Patrol encountered 100,441 migrants at the southern border -- a 28% increase compared to January 2021 -- and carried out 72,113 expulsions. 

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Roughly 9,500 unaccompanied minors are in HHS custody while about 4,500 await processing at CBP facilities, The Associated Press reported Thursday. 

CBP cannot expel children under U.S. law, so they are temporarily held at facilities like the one in northeast El Paso, which has a capacity of 1,040 migrants. The El Paso facility and others at the southern border are stretching to their max, creating crowded conditions amid the coronavirus pandemic as the Biden administration works to find more space and resources for those coming to the border.

Travelers, left, waiting in line to cross a customs area into the United States at the McAllen-Hidalgo International Bridge look on as a group of migrants, right, are deported to Reynosa, Mexico. (AP Photo/Julio Cortez)

"Catch-and-release policies pose additional risks to public health in the midst of the ongoing COVID-19 pandemic," the senators wrote. "The Biden Administration has expressed a purported commitment to ending the pandemic; however, news reports suggest that it now plans to keep some who are apprehended by DHS personnel in custody for just 72 hours before releasing them into American communities."

On Friday, Mayorkas visited an El Paso CBP facility, where he received a briefing "on the processing, shelter, and transfer of unaccompanied children," along with a bipartisan group of senators, according to DHS, He did not speak to the press.

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Republicans have argued that Biden's immediate rollback of Trump-era policies created the current influx of migrants at the border, though the number of encounters at the border has been increasing since April 2020, according to CBP.

Trump critics argue that the former president's "Remain in Mexico" policy put migrants seeking U.S. citizenship in danger of trafficking and violence in that country.

In this photo taken by a drone, migrants are seen in custody at a U.S. Customs and Border Protection processing area under the Anzalduas International Bridge, Thursday, March 18, 2021, in Mission, Texas. . (AP Photo/Julio Cortez)

The nine senators are asking for more information from DHS and HHS, including a breakdown of the number of migrants detained since Jan. 20, the number of migrants tested and vaccinated for COVID-19, estimates for how much time individuals spend in CBP custody before and after testing, and future border apprehension projections.

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More than 40 House Republicans also sent a letter to Beccera on Friday expressing "extreme concern" over the number of unaccompanied minors arriving at the border.

A number of GOP lawmakers have traveled or have plans to travel to the southern border to get first-hand accounts of the situation. Blackburn is traveling to Arizona on Sunday to "get the facts and see the crisis firsthand," she said in a statement.