A proposed rule could make it much harder for undocumented immigrant children who come to the United States to stay with their relatives.

Currently, when unaccompanied children arrive at the border—the bulk of whom flee violent, dangerous countries and look for asylum in the U.S.—they usually go into the custody of the Department of Health and Human Services (HHS). HHS then tries to find parents or relatives who can care for them while their immigration proceedings move forward. Those people are called sponsors. And if HHS can’t find sponsors for the children, they stay in foster care or shelters.

Last week, however, the Department of Homeland Security proposed a rule that would have Immigration and Customs Enforcement (ICE) check the immigration status of sponsors looking to care for these children, as well as the immigration status of any other adults who live in the sponsors’ homes. The rule would have ICE get biometric data—potentially meaning fingerprints or retinal scans—of those individuals.

Because the relatives of undocumented children are sometimes themselves undocumented, immigrant rights advocates warn that the new rule could put some potential sponsors in fear of deportation, discouraging them from coming forward to take in unaccompanied children.

“The proposal has the potential to drastically expand ICE’s enforcement dragnet,” said Katie Shepherd of the American Immigration Council. “It may ultimately harm—not help—unaccompanied children whose sponsors and loved ones end up being targeted and detained by ICE due to the increased screening.”

Shepherd added that children may end up languishing in foster care or HHS shelters as a result of the rule change, at a much higher cost to U.S. taxpayers.

The rule, which was first reported on by PoliticoPro, can be implemented without congressional approval. Currently, DHS is hearing comments on the rule. The deadline for commenting is June 7.

The rule comes in the wake of a report from the Senate Homeland Security and Governmental Affairs Committee that noted some children placed with sponsors in 2014 ended up being forced into difficult conditions (PDF). In one case, children ended up working on a Marion, Ohio, egg farm for 12 hours every day.

Lawmakers criticized HHS officials over the report’s findings at a hearing on April 26 of this year.

“Once these unaccompanied kids are in the United States, we have a duty to ensure they’re not trafficked and they’re not abused,” said Sen. Rob Portman (R-OH).

The Department of Homeland Security directed The Daily Beast to that hearing for comment on the rule change. In the hearing, acting assistant secretary at HHS’ Administration for Children and Families, Steve Wagner, spotlighted the horror of children being trafficked and said that increased information sharing between ICE and HHS is designed to protect children from exploitation.

“We had a change of administration,” Wagner said. “There’s new political leadership at both departments that insists on taking a look at the situation governing UAC, precisely because of what this committee highlighted in the terrible Marion, Ohio case. We want to make sure that’s never repeated.”

But advocates say the rule changes won’t make kids safer.

“It’s blatant disregard for the best interests of these children,” said Megan McKenna of Kids In Need of Defense.

“This is so expansive,” she continued. “It’s not only checking the sponsors, but anyone in the household. The effects are enormous, and it would just serve to drive people further underground and harm children in deep and permanent ways.”

ICE has made a host of policy changes under the Trump administration impacting women and children. The agency ended its practice of releasing pregnant women from detention, as The Daily Beast first reported—a change some advocates say will result in more miscarriages. And last week, the Justice Department announced that when family units cross the border into the U.S., it will separate parents from their children.