How the nine U.S. Supreme Court justices interpret six words will determine whether millions of Americans, including about 67,000 Mainers, will continue to receive subsidized health insurance.

The court will begin hearing oral arguments Wednesday in King v. Burwell, a case that many health care, legal and political observers have described as the most serious threat to the Affordable Care Act, the sweeping health care law signed by President Obama in 2010. The court’s ruling isn’t expected until early summer, but the prospect of skyrocketing premiums, the loss of coverage or a so-called death spiral for the law has advocates of the ACA nervous and calling on state lawmakers to prepare contingency plans.

Whether Gov. Paul LePage thinks Maine needs to take any steps is unknown. His administration declined to respond to several requests for comment.

If the court strikes down the Affordable Care Act subsidies and the law’s fate is left in the hands of a Congress gripped by partisan gridlock, LePage could be among the 34 governors who will be forced to handle the fallout.

SUBSIDIES OUTSIDE STATE EXCHANGES?

The court’s decision will revolve around the interpretation of six words in the ACA, which states that consumers may obtain subsidies that lower the cost of the premiums for insurance they purchase on “an exchange established by the state.”

But only one-third of the states have established their own exchanges. The majority opted to join the exchange operated by the federal government.

The plaintiffs in the case argue that the six words should be strictly interpreted, and that only state-run exchanges can offer plans that qualify for a subsidy. On the other hand, the Obama administration contends that Congress didn’t intend the law to be interpreted so narrowly, and that it fully expected the subsidies to be available on the federal exchange.

The impacts of the case dominated discussion at a Feb. 21 meeting of the National Governors Association in Washington, D.C., where Republican governors who have resisted the law were suddenly discussing contingency plans if the court rules for the plaintiffs.

“It has been the topic of the day,” South Carolina Gov. Nikki Haley, a Republican, told The Washington Post last month. “I mean, it is what all governors are talking about. You’re going to hear the governors be very loud about this.”

GOVERNOR’S INTENTIONS UNCLEAR

LePage, however, has been silent. He did not attend the NGA meeting.

It’s not clear what, if anything, the governor would do to ensure that 67,000 Mainers continue to receive subsidies for private insurance if the court rules against the administration; whether he has appealed to the state’s congressional delegation for a solution; or whether he would move to establish a state exchange or consider other options.

The administration’s only response to questions on the matter has been to indicate that Attorney General Janet Mills, a Democrat, has joined a friend-of-the-court brief urging the court to not rule for the plaintiffs and to retain the subsidies. The administration has not indicated whether LePage supports Mills’ position.

Mary Mayhew, the governor’s health and human services commissioner, declined to weigh in Tuesday.

“I’m going to refer you to the governor’s office on that one,” Mayhew said after testifying before the Legislature’s budget writing committee.

SUBSIDIES PART OF MAINECARE DEBATE

The availability of subsidized insurance became a key talking point for the administration and Republicans during pitched battles in the Legislature over the expansion of MaineCare, the state’s version of Medicaid. LePage argued that Maine should reject Medicaid expansion because the majority of its beneficiaries would qualify for subsidies on the ACA exchange. He raised the prospects of subsidies again when he was asked about vetoing several Medicaid expansion bills during a gubernatorial debate in October.

“The federal exchanges will allow anyone from 100 percent on up to 400 percent (of the federal poverty level for a family of four) to qualify for large subsidies,” he said. “We need to maximize that aspect of it. Take those that do not qualify and then find a way to get them insurance.”

Nearly 90 percent of the 74,792 Mainers who have purchased health insurance during the two enrollment periods since the law went into effect receive some kind of subsidy. According to a national analysis by the Urban Institute, 80 percent of the adults who would lose the subsidies are working, 46.5 percent full time and 33.7 percent part time. If the subsidies through federal exchanges are struck down, the institute estimates that 73 percent of part-time workers would become uninsured.

UNAFFORDABLE WITHOUT SUBSIDIES

Andrea Irwin, at Consumers for Affordable Health Care, said many Mainers receiving subsidies could be forced to drop the coverage without assistance.

Gordon Smith, vice president of the Maine Medical Association, said in a statement that the subsidies are “a crucial piece of the puzzle.”

“We have seen firsthand the consequences when patients delay or avoid trips to the doctor because they cannot afford it,” he said. “Coverage has enabled health care professionals to better provide preventive care and ensure that Maine people are healthier.”

Mitchell Stein, a Cumberland-based independent health-policy analyst, said if the plaintiffs were to win the case, the individual marketplace created by the ACA would likely go into a “death spiral.”

“Without the subsidies helping to pay their premiums, only the oldest, sickest patients would stay in the insurance pool,” Stein said. He said the pattern would keep repeating, and the insurance pool would continue to get older and sicker until premiums were out of reach for most people. Under the ACA, insurance companies are forbidden from refusing to insure people with pre-existing medical conditions.

STRATEGY TO RETAIN COVERAGE

Whether the Supreme Court’s conservative majority will agree with the plaintiffs has triggered broad speculation in the national media. Locally, however, advocates for the law say Maine should be ready with alternatives to ensure that state residents receiving subsidized coverage can keep it.

“Maine has one of the strongest enrollments in the country and people have a need for subsidized insurance,” Irwin said. “I really do think that there’s a role for the Legislature to play here.”

Advocates of the law are hoping that the Legislature will retain a stakeholder group that was formed in 2013 to review the health exchanges. That group, the Maine Health Exchange Advisory Committee, filed its last report in November and would need to be reconvened by the Legislature. Irwin said the group could help create “an entity in which Maine could have its own exchange, but it would take time.”

Kevin Lewis, executive director of Maine Community Health Options, a new cooperative that sells health plans on the exchange, is already working with legislators on a state “fix.” It would allow Maine to establish a state-based marketplace but contract with the federal government to provide all of the same services currently available through healthcare.gov, the online marketplace.

Lewis said the fix would be “semantical,” but in his view the plaintiffs’ case against the government is semantical.

He doesn’t know whether the LePage administration would support the proposal.

Staff Writer Joe Lawlor contributed to this report.