BALTIMORE (Reuters) - A U.S. judge signaled skepticism on Wednesday toward a bid by President Donald Trump’s administration to block a lawsuit by the state of Maryland seeking to preserve the Obamacare law in a case that also challenges Trump’s appointment of Matthew Whitaker as acting attorney general.

FILE PHOTO: A sign on an insurance store advertises Obamacare in San Ysidro, San Diego, California, U.S., October 26, 2017. REUTERS/Mike Blake/File Photo

At a hearing before U.S. District Judge Ellen Hollander in Baltimore, Justice Department attorney Hashim Mooppan declined to disclose whether Whitaker is involved in deciding the future of the 2010 healthcare law, formally called the Affordable Care Act, after a judge in Texas last week found it unconstitutional.

Whitaker, a Trump political loyalist named after the Republican president ousted Jeff Sessions as attorney general last month, is facing a series of legal challenges to the legality of his appointment.

The lawsuit by Democratic Maryland Attorney General Brian Frosh asks Hollander to declare Obamacare constitutional and to find that Whitaker was unlawfully appointed. Trump’s administration has worked to undermine Obamacare after Congress failed in a Republican effort to repeal the law.

The administration asked Hollander to throw out Maryland’s case and argued the state lacked legal standing to sue because it cannot prove it has been harmed merely by a decision by Sessions while he was attorney general not to defend Obamacare in the Texas case.

On Friday, U.S. District Judge Reed O’Connor in Fort Worth ruled that the Affordable Care Act, championed by Trump’s Democratic predecessor Barack Obama, was unconstitutional following revisions to the tax code made last year by Congress, which removed a penalty for failing to obtain health insurance. The law was challenged by a group of states including Texas.

Mooppan told Hollander if Maryland wanted to defend the constitutionality of Obamacare, it could have joined other states that intervened in the Texas case to protect the law. Mooppan said Maryland also had not sustained any injury because the U.S. Health and Human Services Department pledged to continue enforcing Obamacare pending the conclusion of the litigation despite O’Connor’s ruling in Texas.

“What injures Maryland is what happens in the real world. What we write in legal briefs cannot injure Maryland,” Mooppan said.

Hollander appeared skeptical, noting that Trump’s prior Twitter posts supporting the dismantling of Obamacare, coupled with O’Connor’s order, injected uncertainty about the health insurance marketplace’s future and could lead one to reasonably believe the law may not be enforced.

“Doesn’t Maryland have to take steps now to protect itself?” the judge asked. “Can it do nothing to protect itself while all of this is playing out? What are you supposed to do? Sit back?”

Tom Goldstein, one of two attorneys arguing for Maryland, said the state was injured by the fact that an official illegitimately appointed is presumably presiding over Obamacare’s future.

Maryland sought an injunction barring Whitaker from serving as acting attorney general, saying his appointment violated the Constitution and a federal law governing the Justice Department’s line of succession.

If Hollander finds Obamacare constitutional, that would create a conflict with the Texas ruling and could lead the U.S. Supreme Court to weigh in. The high court previously has upheld Obamacare.

Hollander asked fewer questions regarding Whitaker’s appointment and indicated the issue could become moot. Trump on Dec. 7 said he would nominate William Barr to become attorney general on a permanent basis. He would replace Whitaker, pending a Senate confirmation process likely in early 2019.

The number of Americans who signed up for 2019 Obamacare insurance plans fell by about 4 percent compared to the prior year, government data released on Wednesday showed.