The lawsuit filed in U.S. District Court of Maryland comes as the latest push to scrap the Affordable Care Act has pressed ahead in Texas. Last week, 20 Republican-controlled states asked a federal judge to bring the law to a halt, arguing that the entire health statute was rendered unconstitutional after Congress repealed the "individual mandate" that required most Americans to buy insurance or risk a tax penalty.

Democrat Brian Frosh, the mid-Atlantic state's attorney general, is seeking a declaratory judgment in U.S. District Court of Maryland that ACA is indeed constitutional and the Trump administration must stop trying to "sabotage" the Obama-era Affordable Care Act.

"Their attempts to sabotage this life-saving law and jeopardize the health of Marylanders who rely on it cannot stand," Frosh said in a statement announcing the lawsuit. "We are taking action to protect and ensure health care coverage for every Marylander and all Americans."

The Texas case now in front of a Fort Worth federal judge is the most high-profile legal challenge to the ACA under Trump, whose administration is not defending the law in court. Maryland's effort, in turn, is the latest in a broad effort by attorneys general in various blue states — already fighting Trump policies on other fronts — who have been pushing back against a slew of efforts to undercut or eradicate the Affordable Care Act.

After years of trying to demolish former President Barack Obama's health care law, GOP leaders still lack the votes to fully repeal it and the upcoming midterm elections in the U.S. might push that goal further out of reach. Annulling the statute was one of Trump's top campaign promises.

Maryland's lawsuit says that more than 100,000 state residents have obtained private health coverage and uncompensated care costs have declined by some $300 million under the health law. The lawsuit says eliminating the ACA would cause "immediate and long-term harm" to Maryland by imperiling people's health and destabilizing its care systems and insurance markets.

Last month, Maryland officials announced federal approval of a waiver to create the nation's largest health reinsurance program, a step designed to protect insurers from skyrocketing claims and hold down rates in the struggling individual market of the state's health care exchange. Maryland lawmakers who sponsored legislation in the last session said the program was needed to rescue the state's individual health exchange market, which faced collapse over sharply rising rates.

There was no immediate comment from Health and Human Services, which is among the various U.S. departments listed as defendants in Maryland's lawsuit.