"We urge you to redouble the Administration’s efforts to close this cruel chapter in the Trump Administration’s history and reunite these families immediately," the letter, addressed to Department of Homeland Security Secretary Kirstjen Nielsen and other senior officials, said.
The lawmakers added that it was shocking that the federal government has been unable to resolve this human tragedy with all the means at their disposal.
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"We demand immediate answers and accountability from an administration that tore families apart without any consideration for its destructive consequences," Congressional Hispanic Caucus Chairman Lujan Grisham said in the letter.
Nearly 2,700 migrant children were separated from their parents during the implementation of the Trump administration's zero tolerance policy at the US border with Mexico. The decision was meant to deter illegal migration into the United States. However, in July, US President Donald Trump ordered a halt to the separations after widespread public criticism in response to the practice. The administration, however, missed a court-ordered deadline to reunite the families.