The Homeland Security Department is proposing a new rule that would allow for the prolonged detention of undocumented migrant children by replacing a 1997 legal settlement that President Donald Trump has called a “loophole” causing more illegal immigration.

The 203-page proposed rule, published jointly with the Health and Human Services Department in the Federal Register on Thursday, would trigger the end of the so-called Flores settlement. A federal judge has ruled the settlement means children cannot be held in detention for longer than 20 days and should be released with a parent if possible.

Under the proposed rule, DHS would be able to hold children in custody together with their parents for the duration of their immigration proceedings, ending for some migrants a practice that Trump has derided as “catch-and-release.”

“This rule addresses one of the primary pull factors for illegal immigration and allows the federal government to enforce immigration laws as passed by Congress,” Homeland Security Secretary Kirstjen Nielsen told The Washington Post.

The proposed rule “would satisfy the basic purpose of the [Flores settlement] in ensuring that all juveniles in the government’s custody are treated with dignity, respect, and special concern for their particular vulnerability as minors,” DHS said in the Federal Register.

The proposed rule comes on the heels of nationwide uproar over the administration’s separation of more than 2,500 migrant children from their parents last spring. Around 500 children have still not been returned to their parents and remain in custody, the administration said last week.

After ending the policy under bipartisan pressure from lawmakers, Trump ordered the Justice Department to seek an alteration of the Flores settlement in order to allow for the prolonged detention of children. But Judge Dolly Gee of the U.S. District Court for the Central District of California refused.

Gee called the administration’s efforts to circumvent the Flores agreement in order to prolong detention “a cynical attempt, on an ex parte basis, to shift responsibility to the Judiciary for over 20 years of congressional inaction and ill-considered executive action that have led to the current stalemate.”

The proposed rule will not take effect immediately and is almost certain to be the target of legal challenges.