Young adult immigrants known as “Dreamers” in 19 US states will be temporarily blocked from getting health insurance through the Affordable Care Act's public marketplace, a federal judge has ruled, limiting an effort by the Biden administration to help immigrants brought to the country illegally as children.

Judge Daniel Traynor of the US District Court in North Dakota issued the order Monday from Bismarck, dealing a setback to a Biden administration rule that was estimated to allow 147,000 immigrants to enrol for coverage. Traynor's ruling came in a lawsuit filed over the policy and will remain in effect until the matter can go to trial.

The ruling applies to immigrants in 19 states where Republican attorneys general sued to avoid having to comply with the new policy. They cited concern over immigrants possibly qualifying for public subsidies available to many people insured under the ACA.

The GOP state officials argued that the rule created earlier this year by the US Centres for Medicare and Medicaid Services would be a strong incentive for immigrants to remain in the US illegally and could creating costs for states. They argued that both the Affordable Care Act and a 1996 law prohibit US government benefits flowing to immigrants living in the US illegally.

“Dreamers” are part of a programme that makes them a low priority for deportation. However, President-elect Donald Trump won the November 5 election promising “the largest mass deportation programme in history.” He will succeed President Joe Biden on Jan. 20.

Traynor, a Trump appointee during his first term in office, concluded through what he called “a common-sense inference” that access to subsidised ACA coverage is a powerful incentive for people to remain in the US illegally, creating a substantial risk that states will “suffer monetary harm.”

Federal law gives CMS the authority to determine whether someone is living in the US legally, but, Traynor wrote, “It by no means allows the agency to circumvent congressional authority and redefine the term lawfully present.'”

CMS said in a statement Tuesday that it is reviewing the lawsuit but does not comment on litigation.

Nicholas Espiritu, deputy legal director of the National Immigration Law Centre, said some “Dreamers” have been waiting for more than a decade to get “life-sustaining” health coverage through the ACA.

“Judge Traynor's ruling is both disappointing and wrong on the law,” Espiritu said, promising his group would continue to fight the issue.

But Kansas Attorney General Kris Kobach called the decision “a victory for the rule of law." He told reporters after a hearing in Bismarck in October that the Biden administration sought to redefine what it means to be an immigrant living in the US legally by “executive fiat,” calling the rule “Alice in Wonderland stuff.”

North Dakota Attorney General Drew Wrigley added then that American taxpayers, through Congress, determine how the federal government treats immigrants living in the US illegally.

“And it doesn't always come across as friendly and nice and cuddly, but it speaks to the access to our health care system, the cost of our healthcare system, and the burden on the American public, the taxpayer,” he said.

Kansas and North Dakota are the lead plaintiffs in the lawsuit filed in August. They've been joined by Alabama, Arkansas, Florida, Idaho, Indiana, Iowa, Kentucky, Missouri, Montana, Nebraska, New Hampshire, Ohio, South Carolina, South Dakota, Tennessee, Texas and Virginia.

“Thankfully, the court put another nail in the coffin of Biden's radical left-wing agenda,” Alabama Attorney General Steve Marshall said in a statement Tuesday.