* Health partisans on both sides see reason for optimism

* Law’s opponents say mandate clearly in trouble

* Advocates see solid support among liberal justices

* Tough questions may suggest ‘non-ideological’ ruling

By David Morgan and Ian Simpson

WASHINGTON, March 27 (Reuters) – The Supreme Court is not expected to rule on the U.S. healthcare law’s contentious individual mandate for another three months.

But that did not stop partisans on both sides of the political battle from claiming – or at least trying to salvage – an early victory in the court of public opinion on Tuesday.

The shouting match began well before the high court started hearing oral arguments on the case this week.

It escalated measurably after the justices wrapped up their rapid-fire q uestions on Tuesday on the constitutionality of the provision that requires most Americans to have health insurance in 2014.

While no one would predict a final ruling, some Republicans appeared jubilant over signs of an ideological split that could position the court’s 5-4 conservative majority in opposition to the mandate.

“Based on my reading of the … hearings today, it is doubtful that the individual mandate will survive,” Senator Mike Lee of Utah said in one of several Twitter messages Senate Republicans issued after Tuesday’s hearing concluded.

But advocates of the healthcare overhaul saw a silver lining, saying the tone of the justices’ discourse appeared to favor the law.

“There was a majority of the court in favor of upholding … the individual mandate,” said Doug Kendall of the liberal Constitutional Accountability Center.

The mandate is the linchpin of President Barack Obama’s signature policy to provide healthcare coverage to more than 30 million uninsured Americans under the 2010 Patient Protection and Affordable Care Act, or ACA.

It is being challenged by 26 states and an independent business group that want the provision overturned on the grounds that it exceeds the federal government’s constitutional authority.

Outside the court’s Greco-Roman colonnade, the law and its main provision are at the center of a vitriolic political debate between presidential candidates, lawmakers and allied groups that could help determine who controls the White House and Congress after the Nov. 6 election.

SOURCES OF SUPPORT

But not everyone who opposes the law saw Tuesday’s proceedings as a victory.

“It didn’t look to me as if it was a slam dunk from any perspective,” said Douglas Holtz-Eakin, president of the conservative American Action Forum, who attended the hearing.

Advocates of the law said the hearing demonstrated solid support for the mandate from the court’s four liberal justices – Ruth Bader Ginsburg, Sonia Sotomayor, Elena Kagan and Stephen Breyer.

That means the measure could be upheld if one conservative justice joins them and some saw evidence that Justice Anthony Kennedy could do so.

“Justice Kennedy asked very tough questions. And yet he described the unique dynamics of the healthcare market himself, more so than anyone else,” said Ethan Rome, executive director of Health Care for America Now, a coalition of union and liberal groups that has been lobbying for reform since 2008.

“Not all healthcare advocates saw today as a good day. But that’s the wrong way to read it,” he said. “Kennedy needs to ask the toughest questions to assure conservatives that any non-ideological judgment will be based on the merits.”

Ron Pollack, executive director of the healthcare consumer advocacy group Families USA, said the court’s final ruling will depend on how many justices view the mandate as an instrument for regulating healthcare rather than spurring insurance sales.

“If it’s healthcare, they’ll come out in a way that understands healthcare consumes one out of every six dollars in the economy and that it’s rational for Congress to regulate it,” Pollack said.

Regardless of how the Supreme Court rules on the legal issues, healthcare reform’s ultimate fate could lie in the political realm, depending on the outcome of November elections.

“If Senate Republicans become the majority next year, the first item on the agenda of the new Senate Republican majority would be the repeal of Obamacare (ACA) and the replacement of it with something that makes more sense and is targeted at the problems that we actually have in American healthcare,” said Senate Republican leader Mitch McConnell.