Congressional Republicans sent a message Monday that they hope the Supreme Court and voters will hear: The country's health care system won't crumble if the justices obliterate a bedrock feature of President Barack Obama's heath care law.

Three top senators said if the court invalidates federal subsidies that help millions of Americans buy coverage under Obama's law, they have a plan to protect them and create "better" insurance markets by giving states more leeway to decide what insurers must cover.

But in an opinion article in Monday's Washington Post, GOP Sens. Lamar Alexander of Tennessee, John Barrasso of Wyoming and Orrin Hatch of Utah offered scant detail, saying nothing about how much assistance they would provide, its duration or how they would pay for it.

They also did not describe how they would push such a package through Congress with Republicans split about how to respond to such a court ruling and so divided that even a must-pass bill financing the Homeland Security Department has bogged down. Or how they would get Obama, who opposes any weakening of his 2010 law, to sign it.

"First and most important: We would provide financial assistance to help Americans keep the coverage they picked for a transitional period," the senators wrote. "It would be unfair to allow families to lose their coverage, particularly in the middle of the year."

The article appeared two days before the Supreme Court hears arguments in a case brought by conservatives and Republicans claiming that tax credits helping millions of people who buy health coverage from a federally run insurance marketplace in 37 states are not legal. Most of those states are GOP-run and represented in Congress by Republicans.

The only credits Obama's law allows are for people in the 13 states running their own marketplaces, the plaintiffs say.

The Obama administration and Democrats who enacted the law over unanimous GOP opposition say it was always intended to provide subsidies in all the states.

Underscoring the case's significance, lawmakers from both sides planned to attend Wednesday's court arguments.

Republicans set to watch included Alexander, Barrasso and Michigan Rep. Fred Upton, chairman of the House Energy and Commerce Committee. Also ready to attend were Washington Sen. Patty Murray, top Democrat on the Senate Health, Education, Labor and Pensions Committee; Oregon Sen. Ron Wyden, lead Democrat on the Senate Finance Committee; and Michigan Rep. Sander Levin, top Democrat on the House Ways and Means Committee.\

A court decision is expected in June.

Republicans weren't the only lawmakers making statements that seemed aimed as much at the court's nine justices as at the public. Last week, Health and Human Services Secretary Sylvia Burwell said nullifying the subsidies would cause "massive damage to our health care system" and said the administration would have no way to fix it.

In their column, the three senators call the case "an opportunity" to reshape the law and say they "have a plan to protect these people and create a bridge away from" the statute.

Democrats say the law has forced insurers to cover more benefits and cite figures showing a dramatic reduction in the number of uninsured Americans.

Alexander chairs the Senate Health, Education, Labor and Pension Committee, Hatch heads the Senate Finance Committee and Barrasso is in the Senate Republican leadership.