Nearly two-thirds of Americans want Congress to ensure that residents in every state can receive insurance subsidies though the
Asked whether lawmakers should pass a law "so that people in all states can be eligible for financial help," just one-quarter of those surveyed said no, according to the poll by the nonprofit Kaiser Family Foundation.
The legal challenge, brought by conservative activists, argues that a strict reading of the health statute makes subsidies available only in states that established their own insurance marketplaces through the law, something that just 13 states and the District of Columbia did.
The rest of the states rely on the federal government to operate all or part of the marketplace for them.
The marketplaces — which opened in 2013 and now cover about 10 million people — allow Americans who don't get health benefits at work to shop online among plans that must offer basic benefits and cannot turn away customers, even if they are sick.
Consumers making less than four times the federal poverty level — about $47,000 for a single adult and $97,000 for a family of four — qualify for subsidies.
If the court backs the challengers, more than 6 million people are expected to become uninsured, throwing insurance markets in dozens of states into chaos.
The justices are expected to rule on the case by the end of this month. If they side with the challengers, Congress could preserve the subsidies with a one-page bill clarifying that aid is available in all states, a solution that President Obama has indicated he would request.
But congressional Republicans have said they won't go along with that unless the president agrees to major changes in the health law, probably setting up a high-stakes political struggle in Washington.
Any extended stalemate in Washington would put pressure on states to undertake the potentially expensive and complicated task of setting up their own marketplaces to retain their residents' access to subsidies.
Just two states — Delaware and Pennsylvania — have made plans to do that. On Monday, the Obama administration indicated it would support the states' proposals.
Fifty-five percent of residents of states that currently rely on the federal government favor that move, the Kaiser poll found; 32% say the state should not create its own marketplace.
State action is preferred even by Republicans, who favor a state marketplace over no action, 44% to 42%, despite the fact that the health law remains deeply unpopular with the GOP. Nearly 70% of Republicans view it unfavorably.
Overall public opinion about the health law remains closely divided, with 42% of Americans holding a negative view and 39% holding a positive view.
The Kaiser tracking poll of 1,200 adults nationwide was conducted June 2-9 and has a margin of error of plus or minus 3 percentage points; the margin is higher for questions based on subgroups.