The Trump administration is calling for the expanded use of family detention for immigrant parents and children who are stopped along the US-Mexico border.
But the move has been condemned as a cruel and ineffective attempt to deter families from coming to the United States.
Immigration authorities on Friday issued a notice that they may seek up to 15,000 beds to detain families.
The Justice Department has also asked a federal court in California to allow children to be detained longer and in facilities that do not require state licensing while they await immigration court proceedings.
“The current situation is untenable,” August Flentje, special counsel to the assistant attorney general, wrote in court filings seeking to change a longstanding court settlement that governs the detention of immigrant children.
The more constrained the Homeland Security Department is in detaining families together during immigration proceedings, “the more likely it is that families will attempt illegal border crossing”.
The proposed expansion comes days after a public outcry moved the administration to cease the practice of separating children from their migrant parents on the border.
More than 2,300 children have been taken from their parents since Homeland Security announced a plan in April to prosecute all immigrants caught on the border.
In all, about 9,000 immigrants traveling in family groups have been caught on the border in each of the last three months, according to federal authorities.
Immigrant advocates contend detention is no place for children and insist there are other alternatives to ensure they and their parents attend immigration court hearings, such as ankle bracelets or community-based programmes.
The federal court ruled several years ago that children must be released as quickly as possible from family detention.
“It is definitely not a solution under any circumstances,” said Manoj Govindaiah, director of family detention services at the Raices advocacy group in Texas.
“At no point should a child be incarcerated, and children need to be with their parents.”
Immigration and Customs Enforcement currently has three family detention facilities — a 100-bed centre opened in Pennsylvania in 2001 and two much larger facilities opened in Texas in 2014.
Only the Pennsylvania facility can house men, and all of the detainees at the Texas centres are women with children.