A group of Democratic senators wrote a letter to the Department of Homeland Security chief expressing "deep concerns" about the end to Title 42, a Trump-era policy allowing for the rapid removal of migrants encountered at the border. 

The policy, originally implemented in March 2020, was struck down earlier this month by U.S. District Court Judge Emmet Sullivan, who ruled that it violates the Administrative Procedure Act. 

Migrants Arizona

FILE: Migrants attempting to cross in to the U.S. from Mexico are detained by U.S. Customs and Border Protection at the border August 20, 2022, in San Luis, Arizona.  (Nick Ut/Getty Images)

It will officially expire on Dec. 21 amid record-breaking levels of immigration, with more than 2.3 million migrant encounters at the border in fiscal year 2022. 

DHS PUSHES BACK AGAINST MCCARTHY CALL FOR MAYORKAS TO RESIGN OR FACE POTENTIAL IMPEACHMENT 

"Record annual encounters have led to untenable situations," Sens. Kyrsten Sinema, D-Ariz., Mark Kelly, D-Ariz., Jon Tester, D-Mont., and Maggie Hassan, D-N.H., wrote in a letter to DHS Secretary Alejandro Mayorkas that was made public Monday. 

"In Arizona, shelters have been forced well beyond capacity. This month, El Paso has seen over 700 migrants released directly onto city streets due to overcrowding. This is not safe, and creates a dangerous situation for migrants and communities."

El Paso migrant center

A U.S. Border Patrol agent speaks with Central American immigrants at the border fence. (John Moore/Getty Images)

Mayorkas testified before the Senate earlier this month, saying that the Biden administration has a plan once Title 42 expires. 

"We are enhancing the consequences for unlawful entry, especially with respect to individuals who seek to evade law enforcement, including removal, detention and criminal prosecution when warranted," Mayorkas said. 

Migrants, Border Patrol agents clash near El Paso, Texas

Venezuelan migrants returning to Mexico down the Rio Grande after crossing into the United States illegally on October 31, 2022.  (REUTERS/Jose Luis Gonzalez)

CLICK HERE TO GET THE FOX NEWS APP

Republicans, meanwhile, have pledged to investigate the DHS once they retake the House of Representatives in January, calling for Mayorkas to either resign or be impeached. 

"He cannot and must not remain in that position," McCarthy said. 

"If Secretary Mayorkas does not resign, House Republicans will investigate every order, every action and every failure to determine whether we can begin an impeachment inquiry."

Fox News' Adam Shaw contributed to this report.