The US would be allowed to indefinitely detain migrant families who cross the border illegally, under a regulation unveiled Wednesday by the Trump administration that would eliminate a previous 20-day limit as judges weigh their asylum requests.

The proposed rule, which would replace a 1997 court settlement that limits how long US authorities can hold migrant children, is bound to spark a new court fight about immigrants’ rights.

President Trump also told reporters Wednesday that his administration was seriously considering ending the right of citizenship for children born to noncitizens in the US.

“We’re looking at that very seriously, birthright citizenship, where you have a baby on our land, you walk over the border, have a baby – congratulations, the baby is now a US citizen. … It’s frankly ridiculous,” the president said on the South Lawn.

Homeland Security officials say they have caught 390,000 family units since October as immigration authorities have struggled to handle a surge of migrants fleeing violence and poverty in Central America.

“Today, the government has issued a critical rule that will permit the Department of Homeland Security to appropriately hold families together and improve the integrity of the immigration system,” Acting Homeland Secretary Kevin McAleenan said in a statement.

“This rule allows the federal government to enforce immigration laws as passed by Congress and ensures that all children in US government custody are treated with dignity, respect, and special concern for their particular vulnerability.”

Team Trump has been pressing the Department of Homeland Security to replace the so-called Flores agreement, which requires the US to keep children in the least restrictive setting and to release them as quickly as possible — generally after 20 days.

The new regulation — which requires a federal judge’s approval before it could go into effect — would establish standards for conditions in detention centers. It would specifically abolish the 20-day limit, which prompted Trump to criticize the “catch and release” of migrants into the US.

The proposed regulation is scheduled to be published in the Federal Register on Friday and would take effect 60 days later, though it will likely be delayed because of expected court challenges.

Sen. Chuck Schumer reacted to the new regulation by saying, “the cruelty of the Trump administration knows no bounds.

“Make no mistake: this new rule is about letting President Trump and Stephen Miller keep children in awful conditions for longer periods of time and continue the administration’s horrid treatment of innocent migrant families fleeing unthinkable hardship,” he said, referring to the senior White House adviser and immigration hard-liner.

“Having seen first-hand the awful conditions the Trump administration subjects many migrant families to, it is imperative that the courts immediately block this rule from going into effect,” Schumer added.

The 20-day limit has been in effect since 2015 as a result of a 1997 court-ordered consent decree after a federal class-action lawsuit alleged physical and emotional harm done to migrant children held for long periods.

Peter Schey, a lawyer for the immigrant children in the Flores case and president of the Center for Human Rights and Constitutional Law, said that if the new regulations don’t match the settlement, “they would be in immediate material breach, if not contempt of court.”

“I think all these things are now part of the 2020 campaign,” Schey said.

Schey told CBS News that he expects the judge that oversees the Flores case to reject the White House efforts.

“These regulations do not implement the settlement. In fact, it abrogates the settlements. And so I think their efforts will be futile,” he said.

Schey — who had not yet seen the final regulations, but reviewed a draft published in September 2018 – accused Team Trump of playing politics with children’s well-being.

“They know that the only way the can terminate the settlement is by coming out with regulations that institutionalize it, but they have a history of criticizing the settlement,” he told the network.

“So what is this? I think it’s a politicization of the treatment of children. It’s part of running for reelection. That’s what it’s about,” he added.

The administration hopes to circumvent the 20-day detention limit by creating a federal licensing system to authorize facilities the government can use to hold families with children.

Trump defended the proposed regulation by saying he has the children on his mind.

“It bothers me very greatly. People make this horrible 2,000-mile journey. One of the things that will happen, when they realize the border is closing, the wall is being built, we are building tremendous miles of wall right now, it all comes together like a beautiful puzzle,” he said Wednesday.

“One of the things that is happening, when they see you can’t get into the United States — or when they see if they do get into the United States they will be brought back to their country — they won’t come. And many people will be saved,” he added.

The US currently only has three facilities designed to detain migrant families, two in Texas and one in Pennsylvania.

Under the new regulation, a Homeland Security official told CBS News that these facilities would be subject to an audit from a unspecified third party that would ensure the locations comply with licensing standards.

The official acknowledged that the agency expects the rule to quickly be challenged in court – but that the administration will argue that the rule does not amount to indefinite detention because officials will offer migrant families bond hearings and the opportunity for parole.

With reporting by Nikki Schwab and Post wires