Washington (CNN) A congressional committee is preparing to subpoena the acting directors of two of the Department of Homeland Security's immigration agencies, aiming to compel them to testify over the temporary end to a policy that allowed some immigrants with severe health issues to remain in the US.

House Oversight and Reform Committee Chairman Elijah Cummings wrote in a memo to members on Thursday that he plans to subpoena USCIS acting Director Ken Cuccinelli and Immigration and Customs Enforcement acting Director Matthew Albence to testify on October 17.

"The Committee has tried for more than a month to obtain this information voluntarily, but USCIS and ICE have obstructed the investigation," wrote Cummings, a Maryland Democrat. The committee will also subpoena documents related to the decision.

On August 7, US Citizenship and Immigration Services stopped considering deferred action requests for immigrants with non-military special circumstances -- a way that some immigrants and their families were able to receive US-based health care.

USCIS sent letters to immigrants in August informing them of the change and warning them that they had 33 days to leave the US or face deportation proceedings. Public outcry quickly followed and in September, acting Homeland Security Secretary Kevin McAleenan ordered that USCIS to reverse the decision.

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