WASHINGTON – The Trump administration said Wednesday it was taking steps that would allow it to indefinitely detain undocumented children with their families while their immigration cases are pending.

The move, which Department of Homeland Security officials expect to be challenged in federal court, would end a 20-day limit on detaining children and families. The deadline grew out of a settlement of a class-action lawsuit in 1997, and the administration said it led to a boom in adults bringing children when entering the U.S. illegally.

Advocates voiced concerns that longer detention could harm children.

“We are talking about an agency that required a court order just to provide soap to children in their custody,” said Michelle Brané, senior director for migration rights and justice at the Women’s Refugee Commission, an advocacy group.