HARRISBURG — Gov. Tom Wolf’s administration advanced plans Friday to maintain federal health insurance subsidies for nearly 400,000 Pennsylvanians ahead of a U.S. Supreme Court decision that could wipe out the aid to insurance buyers in some states.

The Democrat wrote to U.S. Health and Human Services Secretary Sylvia Burwell to declare his administration’s intent to take over operation of the insurance marketplace in 2016. The federal government currently operates the marketplace, which is a prominent feature of the 2010 federal health care law designed to extend insurance coverage to 35 million Americans.

“In order to protect 382,000 Pennsylvanians from potentially losing subsidies that help them afford health care coverage, I have written to the federal government outlining a contingency plan to set up a state-based marketplace to ensure no one loses their health coverage,” Wolf said in a statement.

Wolf’s administration said the letter is not binding, but it ensures the option is available next year in case the high court’s ruling is adverse. In any case, approval from the Republican-controlled Legislature would be required for any money needed to run an exchange and potentially for the legal authority, legislative officials said.

“We are concerned about the cost. What are the costs involved and how does (Wolf) propose paying if there are costs involved?” said Steve Miskin, a House GOP spokesman.

The move comes as a number of states are reconsidering the exchanges they run amid financial or operational difficulties. A Health and Human Services Department spokesman said he did not immediately know whether Pennsylvania is the first or only state to take such a step.