The most serious legal challenge to Obamacare in years - King v. Burwell - will go before the Supreme Court in March. The case challenges insurance subsidies to consumers in states that are not operating their own exchange and, if successful, would gut Obamacare well and proper.

In fact, a successful challenge would be so effective in destroying Obamacare, that the Supreme Court may rule that the subsidies are legal in order to avoid the chaos that would ensue in health insurance markets and the health care industry. The rationale for such a decision  would not be without precedent.

Wishing to avoid such a scenario, Republicans want to make it easy for the justiices to rule against the subsidies by crafting a replacement for Obamacare that would mitigate some of the consequences of gutting the law.

Politico:

“What the King case does is gives us an opportunity and a reason to come to a consensus sooner so, when we get the ruling of the Supreme Court in June, we are then prepared to say, ‘Here is what is better for the American people in terms of affordability, quality and choice,’” said Sen. John Barrasso (R-Wyo.), chairman of the Senate Republican Policy Committee.

Barrasso said Republicans earlier had thought that they could put off the replacement debate until the 2016 presidential campaign was well underway, and the GOP nominee put down a marker for the party.

The GOP conversations so far are preliminary, and a breakthrough isn’t imminent. Various Republican proposals have been put forth over the years, but forging agreement requires bridging deep ideological differences among Republicans about the scope of a plan, the role and responsibility of the federal government in health care, and how much to money to spend.

But Barrasso said several groups of lawmakers — members of the Republican Policy Committee and the two Senate committees with jurisdiction over health care — have begun talking about how to build consensus on a replacement plan.

The reasoning behind this is that if the subsidies are declared illegal in all but 13 states, millions of consumers who purchased subsidized plans will not be able to afford them, effectively ending their coverage. This is exactly what Republicans made an issue when Obamacare was rolled out as millions lost their plan despite the president's promise that they could keep it.

But a ruling in King against the White House would hobble President Barack Obama’s signature law and spill over into the rest of the U.S. health insurance system. Without subsidies in two-thirds of the states, the uninsured rate would probably rise, reversing its sharp decline. Premiums could soar if only the sickest people stick with their more expensive coverage.

And the GOP could face a political backlash if people lose coverage from a lawsuit it supported — reminiscent of the fury Obama faced over last year’s plan cancellations.

That threat will dangle over the law until the court rules, likely in June. The uncertainty surrounding the court case also adds complexity to the Republican attempts to undermine the law through repeal votes as well as the budget process known as reconciliation. Republicans may wait until the court’s ruling to decide how they want to use reconciliation.

No matter what strategy they adopt, they won’t be able to get rid of the law legislatively while Obama is in the White House — although they hope that the Supreme Court could create an opening for significant changes.

A replacement plan might offer tax credits to purchase insurance rather than subsidies, high risk pools, and allowing insurance to be sold across state lines, among other ideas. But coalescing around a plan is going to be very difficult considering the vast differences between Republicans in the House and the Senate. And there's no guarantee that the House can even pass a replacement plan given that there are about 50 congressmen who want Obamacare repealed outright with no replacement.

Giving the Supreme Court a reason to rule the subsidies illegal might not seem to be a good reason to keep the guts of Obamacare in place. But Republicans appear to be determined to put their stamp on health insurance reform and King would be their best shot.