The justices on the Supreme Court appeared divided Wednesday during their final day of oral arguments in the case that will decide the future of the Affordable Care Act.
According to The New York Times, the divisions in King v. Burwell appear to be along party lines with the court's four liberal members strongly backing the government's position.
But the positions of Chief Justice John Roberts and Justice Anthony Kennedy were both unclear, leading observers to predict that they will hold the decisive votes in the case's outcome.
"Perhaps you will prevail in the plain words of the statute," Kennedy told a lawyer for the challengers, according to the Times. But he added, "there's a serious constitutional problem if we adopt your argument."
An estimated seven million people in 34 states could be affected by the outcome of the case if the Supreme Court decides that the law prohibits people on the federal healthcare exchange from receiving insurance subsidies.
In many cases, coverage would become unaffordable for those affected, fatally undermining the president's signature healthcare law.
Plaintiffs in the case contend that the plain language of the law should be followed, which states that subsidies are only available to people living in places where the insurance marketplaces were "established by the state."
Roberts, who cast the decisive vote in favor of Obamacare when it was challenged in 2012, was unusually quiet during oral arguments,
The Wall Street Journal reported.
CNN analyst Jeffrey Toobin said the chief justice's views of the case were "almost entirely a mystery,"
The Hill reported.
As for Kennedy, in 2012 he voted to strike down the healthcare law in its entirety.
"Let me say that from the standpoint of the dynamics of federalism, it does seem to me that there is something very powerful to the point that, if your argument is accepted," Kennedy told the plaintiffs, according to The Hill, "the states are being told either create your own exchange or we'll send your insurance market into a death spiral."
Justices Antonin Scalia and Samuel Alito both recognized that a ruling against the law could have a major impact but implied that it should not have a bearing on the court's decision, and appeared to be backing the law's challengers.
Alito said at one point "it's not too late" for states to set-up their own insurance exchanges and floated the idea that the court could delay when the ruling takes effect so that Congress has time to craft a solution.
Critics of the law were cautiously optimistic that the subsidies would be struck down.
"I think our position is persuasive," Oklahoma Attorney General Scott Pruitt told the Journal. "Every state had a choice to make."
But supporters of the law also appeared confident after the session, the Journal said.
"There was a true understanding by all the justices that if they were to rule in favor of the plaintiffs, there would be a disastrous outcome," Ron Pollack, executive director of Families USA, told the Journal.
Meanwhile, White House press secretary Josh Earnest said it would be "unwise" to jump to conclusions based on the questioning of the justices which he said could produce "some erroneous predictions about the likely outcome," according to the Times.
The outcome of the case is not likely to be decided until late June or early July, the Times said.