Agencies within the U.S. Department of Homeland Security (DHS) have offered contradictory accounts of how requests to a humanitarian program known as medical deferred action are now being handled, and by whom — throwing the future of the decades-old program into question.

Massachusetts Rep. Ayanna Pressley said Wednesday she may call for a congressional oversight hearing into the status of medical deferred action after denial letters sent this week had many immigrants and advocates fearing the program's end.

"What's so troubling about this beyond the cruelty of it, is the lack of transparency around the process," Pressley, a Democrat, said. "There was no public comment period, not even a public announcement of this, and so I'm working with my colleagues to get answers and to urge this administration to change course."

Medical deferred action has historically allowed eligible migrants to extend their time in the U.S. in order to receive life-saving medical treatment that advocates say is often only available to them here.

Earlier this week, Boston-area immigrants applying through the program received denial letters from U.S. Citizenship and Immigration Services (USCIS), the agency that has long-handled such requests. According to the apparent form letters, USCIS field offices “no longer consider deferred action requests, except those made according to the U.S. Department of Homeland Security policies for certain military members, enlistees, and their families.”

USCIS said this week that another agency — U.S. Immigration and Customs Enforcement (ICE) — would now be handling those requests.

On Wednesday, however, ICE rejected this claim. An ICE official told WBUR that the agency was not informed by USCIS that USCIS would stop processing the deferral requests. "There is no program at ICE that's going to take over that function," the ICE official said.

"ICE is not going to implement any sort of a program or procedure or policy to take over that function," the ICE official said. "We'd like USCIS to clarify what they mean, and we're working collaboratively to get them to be a little more forthcoming about it."

ICE does consider administrative stay requests, a different process that allows the government to postpone deportation for a variety of reasons. People subject to removal from the U.S. can apply for a stay of up to one year, and there is an option to submit medical evidence as a reason for the request.

The denial letters sent from USCIS to applicants in Massachusetts did not reference administrative stays or say ICE would take up medical deferred action requests. The letters told families and individuals they must leave the country within 33 days.

Many of the people receiving these denials are in the middle of ongoing treatment for illnesses like cancer, epilepsy and HIV. If they don't leave the U.S. before the deadline, the letters warned, they could face removal and future requests to enter the country could be denied.

Legal advocates across the country have reported clients receiving similar letters — none of which mention USCIS' claim that requests will be processed by ICE.

The government has not issued any public notification about this change in policy but instead, in an email, told the American Immigration Lawyers Association:

"The change became effective on August 7, 2019. USCIS field offices are informing the public of the change in person on an individual basis."

Immigration experts estimate thousands of people across the U.S. may be affected. It's difficult to provide an exact number of recipients, because USCIS does not track approvals of deferred action based on type.

This story comes from the New England News Collaborative, eight public media companies, including The Public's Radio, coming together to tell the story of a changing region, with support from the Corporation for Public Broadcasting.