If successful, the move would permanently end the health insurance program popularly known as Obamacare and wipe out coverage for as many as 23 million Americans.
White House chief of staff Mick Mulvaney wants to see if the Medicare chief Seema Verma and the health secretary, Alex M. Azar II, can still work together.
A federal judge said the president had vastly exceeded his legal authority in reducing payments to hospitals for drugs given to Medicare beneficiaries.
Democrats dream of expanding Medicare, but struggle to define the role of the popular private plans that now cover more than one-third of the 60 million Medicare beneficiaries.
States that support the Affordable Care Act said a ruling striking down the law had created “ambiguity” and “poses a dangerous threat to the health care of millions of Americans.”