(Reuters) – U.S. President Donald Trump’s administration has stepped up its attack on the Obamacare health care law, telling a federal appeals court it agrees with a Texas judge’s ruling that the law is unconstitutional and should be struck down.

The Justice Department in a two-sentence letter to the Court of Appeals for the Fifth Circuit filed on Monday said it backed the December ruling by U.S. District Judge Reed O’Connor in Fort Worth that found the Affordable Care Act violated the U.S. Constitution because it required people to buy health insurance.

O’Connor ruled on a lawsuit brought by a coalition of 20 Republican-led states including Texas, Alabama and Florida, that said a Trump-backed change to the U.S. tax code made the law unconstitutional.

The 2010 law, seen as the signature domestic achievement of Trump’s Democratic predecessor, Barack Obama, has been a flash point of American politics since it passed, with Republicans including Trump repeatedly attempting to overturn it.

Democrats made defending the law a powerful messaging tool in the run-up to the November elections when polls showed that eight in 10 Americans wanted to defend the law’s most popular benefits including protections for insurance coverage for people with preexisting conditions. The strategy paid off and Democrats won a broad 38-seat majority in the U.S. House of Representatives.

“The Department of Justice has determined that the district court’s judgment should be affirmed,” Assistant U.S. Attorney General Joseph Hunt and other federal officials wrote in the Monday letter. They said they would file a more extensive legal briefing later.

Obamacare survived a 2012 legal challenge at the Supreme Court when a majority of justices ruled the individual mandate aspect of the program was a tax that Congress had the authority to impose.

In December, O’Connor ruled that after Trump signed a $1.5 trillion tax bill passed by Congress last year that eliminated the penalties, the individual mandate could no longer be considered constitutional.

A group of 17 mostly Democratic-led states including California and New York on Monday argued that the law was constitutional.

“The individual plaintiffs do not have standing to challenge the resulting law because they suffer no legal harm from the existence of a provision that offers them a lawful choice between buying insurance or doing nothing,” they wrote in court papers.

About 11.8 million consumers nationwide enrolled in 2018 Obamacare exchange plans, according to the U.S. government’s Centers for Medicare and Medicaid Services.

About 11.8 million consumers nationwide enrolled in 2018 Obamacare exchange plans, according to the U.S. government’s Centers for Medicare and Medicaid Services.

(Reporting by Scott Malone in Boston; Editing by Bill Trott)