Each year, the U.S. gets about 1,000 applications from immigrant families in the U.S. seeking permission to stay in the country and not face deportation so family members can continue lifesaving medical care that is not available in their home countries.

But the Trump administration recently told families who were granted permission to stay for medical care that their permission to stay has been rescinded and they have 33 days to leave the country. The policy, which was not publicly announced, is being applied retroactively to any requests filed on or before Aug. 7.

In a conference call Thursday with reporters, advocates and Democrats expressed outrage over the rule.

“This is a new low even for Donald Trump,” Sen. Ed Markey, D-Mass., said in a conference call with reporters Thursday.

Among those facing deportation is Jonathan Sanchez, 16, who has cystic fibrosis.

His mother, Mariela Sanchez, told NBC 10 in Boston that her family arrived in the United States in 2016 and she had recently applied for the medical exemption. After losing a daughter to the hereditary and incurable disease because doctors in Honduras did not diagnose it, she knows what would have happened to her son if he was not getting the care in the U.S.

“He would be dead,” she told the station.

“This administration is now deporting kids with cancer. Perhaps that is why it was too ashamed to announce this policy change publicly," said Markey, who has been trying to draw national attention to the issue since it was first reported in Boston by WBUR-FM, a public radio station.

The Department of Homeland Security did not immediately respond to a request for comment from NBC News. In a previous statement, United States Citizenship and Immigration Services (USCIS) has said that it was no longer considering nonmilitary requests for deferred action "to focus agency resources on faithfully administering our nation’s lawful immigration system."

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The change was not made public and members of the public were not given a chance to provide comment before it went into effect. Families simply received letters telling them they had 33 days to leave.

“They are telling these people they need to leave on their own,” Anthony Marino, director of immigration legal services,said on MSNBC’s “The Rachel Maddow Show” about the families with seriously ill relatives now facing deportation.

“I don’t know how they expect parents to pull their children from hospital beds, disconnect them from lifesaving treatments and go some place where they are know they are going to die," said Marino. "But that is what they are telling them to do.”

In Miami, attorney Milena Portillo told The Miami Herald that families who have applied for the medical deferments include a girl with an eye malignancy, a girl with cerebral palsy and the father of three children — who are American citizens — who has a terminal liver illness.

“We as a country, we are losing our humanitarian side,” Portillo told the Herald. “We’re not reviewing case by case, but we’re just giving a blanket ‘no’ to everyone.”

Rep. Ayana Pressley, D-Mass., cited in the Thursday call the case of Samuel, a five-year-old boy from Brazil. She said he is unable to eat solid food and without care at Boston Children’s Hospital will not be able to receive the nutrients he needs to live.

"With this decision, again this administration has hit a new low," Pressley said. "To be fighting for your life, imagine on top of that facing deportation."

The American Immigration Lawyers Association called on the USCIS to reverse the policy change. It has asked people to contact elected leaders to change it.

A backlash over the changes has led to confusion over which Department of Homeland Security agency, the USCIS or Immigration and Customs Enforcement, must enforce the new policy, as the agencies have pointed to each other as having jurisdiction.

Medical deferrals are not the only denials imposed by the administration. USCIS told NBC News that it applies to all other deferred action requests outside of the military and immigrants enrolled in the Deferred Action for Childhood Arrival program or DACA.

The policy change is another in a series of actions the administration has taken that have had direct impact on children, both who are immigrants and those who are U.S. citizens.

The administration has taken numerous children from their parents at the border and some have yet to be reunited.

The administration changed the so-called public charge rule so that immigrants wanting a green card or asking to move to the U.S. must prove they are unlikely to ever need public assistance, such as access to health care.

In the time the rule was being drafted and copies of it were leaked, immigrant parents with American citizen children dropped out of programs such as the Special Supplemental Nutrition Program for Women, Infants, and Children, known as WIC, which provides health care and nutritious food for very young children, even though their children have a right to such programs.

“There can be no other explanation for why you would target such a small and vulnerable community other than if your goal was to spread fear and hardship,” Rep. Judy Chu, D-Calif., said.

“This is all in character for an administration that is separating families and abusing children in prison camps at the border," Chu added.

Chu has filed a bill to defund the public charge rule but said “it’s clear that this administration will not stop looking for any opportunity to wage war on immigrants.”