Republican efforts to replace the federal health law have been given new urgency by the  U.S. Supreme Court.

As soon as this spring, the court could invalidate health insurance subsidies available to millions of Americans if it rules for the challengers in a case called King v. Burwell.

Republicans who hate the Affordable Care Act are rooting for the court to do what they have been unable to accomplish – dismantle a key part of the law. But as the party that controls Congress, some Republicans also fear the potential for a backlash if they don’t have a plan to help those who would effectively be stripped of coverage, many of whom are voters in Republican-led states.

There’s another reason to agree soon on a replacement for the law, instead of continuing their long campaign to repeal it. If Republicans present a reasonable alternative, it could help swing a justice or two who might otherwise worry about the possible ramifications of cutting off the subsidies. Or so the reasoning goes.“The Republicans would love to give the justices some comfort that if they rule against the Obama administration, there will be something there to deal with the fallout,” says Dean Clancy, a Republican strategist and former aide to  former House Majority Leader Dick Armey.

Those pushing the case argue that language in the law limits help to pay for insurance to residents of states that have established their own health insurance exchanges. So far only 13 states have – the rest use the federal exchange.  The administration contends that Congress clearly intended that the subsidy — tax credits based on income — be available in all states, and has declined to discuss any possible contingency plans.

If the court rules against the administration, the impact will fall heavily on Republican-led states, such as Florida and Texas, that didn’t create their own exchanges, increasing pressure on Congress to act. free

“I really do believe that this situation has concentrated the minds of many people on [Capitol] Hill,” says Avik Roy, a senior fellow at the Manhattan Institute and a former health adviser to GOP presidential candidate Mitt Romney. If the Supreme Court rules that subsidies cannot be provided through the federal health exchange, he says, Republicans in the House and Senate “realize if they don’t do something, they will be held accountable for that. Because they are running Congress now, so they can’t blame it on the Democrats.”

Still, putting something on the front burner does not guarantee it will get done. Republicans have been vowing to “repeal and replace” the Affordable Care Act almost since it became law in 2010. So far, the GOP-controlled House has held more than 50 separate votes to repeal or otherwise cancel parts of the law. Replacing, however, has been another story.

“Republicans are united around repeal. And they’re united around replace. But obviously they’re not united around ‘replace with what,’” says Dean Rosen, a health-policy consultant who was a top aide to former GOP Senate Majority Leader Bill Frist and to the House Ways and Means Committee.

Republican health strategist Terry Holt, a former aide to the GOP House leadership, agrees. He says Republicans “are serious about a replacement” for the Affordable Care Act, “but it’s the law, and it’s harder to change law than to make it.”

There are several efforts underway to come up with a consensus Republican alternative to the health law. The repeal bill the House approved Feb. 3 includes language requiring the four main committees that handle health legislation in that chamber to approve a replacement, but no time limit is specified.  Separately, three of those committee chairmen were tasked by House Majority Leader Kevin McCarthy in January to come up with a health bill, again with no specific deadline.

Across the Capitol, two GOP senators with deep backgrounds in health — Finance Committee Chairman Orrin Hatch (R.-Utah) and Richard Burr (R.-N.C.) — along with House Energy and Commerce Committee Chairman Fred Upton (R.-Mich.) have unveiled the outlines of a plan that was first floated last year.

And House Ways and Means Committee Chairman Paul Ryan (R.-Wis.)  has said Republicans in the House are working on a short-term “bridge” for those who could get stripped of their insurance subsidies, although again, no specifics have been offered.

Even with new incentives, getting to specifics won’t be easy, says Clancy, for much the same reasons that have kept Republicans from being able to agree on a health overhaul for the past five years.

“There are pro-business Republicans and pro-market Republicans, and you see the divide on lots of issues, including healthcare,” he says.

For example, the more pro-market, libertarian types “would say let’s get the federal government out of the health insurance business altogether if possible, or at least create a much more voucher-like system with as little centralized control as possible,” he says. But the more traditional pro-business Republicans “are not going to be keen on blowing up the employer-based system.” Currently a majority of Americans still get their insurance through their or a family member’s job.

Another complication, says Rosen, is the impending presidential campaign, and the possibility that several sitting members of the Senate may run. “And you can see that the people who are posturing to be candidates … don’t just want to do Obamacare light,” he said.

Still, the prospect of millions of people in states run by Republican governors and Republican legislatures losing their insurance could be the deciding factor, says Holt. “These are people who have been promised something and are expecting it to continue, and it’s hard to see how you cut people off,” he says.