A top Republican senator accused the Health and Human Services secretary of being "contemptuous" of Congress on Wednesday by sidestepping questions about Obama administration preparations for a Supreme Court challenge to President Obama's health care law.

At a Senate Finance Committee hearing, GOP senators repeatedly asked HHS Secretary Sylvia M. Burwell about her plans should the court rule that federal subsidies for millions of Americans' health insurance are illegal. A decision in the case is expected by June.

As she and other administration officials have done previously, Burwell did not answer directly. She said she is focused on implementing the law.

"That doesn't strike me as working with Congress, but rather contemptuous of Congress' oversight responsibilities," said Sen. John Cornyn, R-Texas, the No. 2  Senate GOP leader. He added later, "It's a very, very serious matter."

Asked in a brief interview if he might explore contempt of Congress charges against Burwell, Cornyn said he would talk to colleagues about possible next steps.

Finance Committee Chairman Orrin Hatch, R-Utah, also challenged Burwell for her responses. Asked afterward about Cornyn's remarks, he expressed doubt about formally pursuing contempt, adding, "I think he was making a point."

Sen. Ron Wyden, D-Ore., defended Burwell for not answering hypothetical questions.

The lawsuit, backed by many Republicans, claims that the 2010 health care law allows government subsidies for health coverage that people buy from state-run insurance marketplaces, not those run by the federal government.

The marketplaces are run by the federal government in 37 states. A court decision invalidating the subsidies in those states could force millions of people to drop coverage that would suddenly become unaffordable, and cause insurance rates to rise for many others as well.