Republicans keep saying theyll be ready to act if the Supreme Court upholds the big legal challenge to Obamacare, thereby wiping out financial assistance for millions of people in two-thirds of the states.

With the clock ticking down to a ruling, its gotten awfully hard to take the GOPs vows seriously.

Most experts expect the court to rule on King v. Burwell , as the case is known, on or around June 29, which is the last official day of its term. A victory for the plaintiffs would cut off tax credits that residents in Florida, Texas and 32 other states now use to pay for health insurance they obtain through Healthcare.gov, the federally operated marketplace.

Those tax credits are worth hundreds, sometimes thousands of dollars a year. They are the equivalent of a discount on insurance premiums and, without them, most of the people now receiving the credits would no longer be able to pay for their health insurance.

The ranks of the uninsured would swell by more than 8 million, according to an estimate by the Urban Institute . The loss of so many customers would likely force insurance companies to raise premiums and withdraw altogether from some markets, affecting even those customers buying directly from insurers rather than through Obamacare's marketplaces.

Under Supreme Court rules , an order would typically take effect within 25 days of its announcement from the bench. In theory, the court could issue a stay delaying its impact. In practice, legal experts consider such a move both unlikely and of questionable significance, given the tight deadlines that insurers and state regulators face for setting next year's premiums.

Infographic by Alissa Scheller for The Huffington Post.

Leaders of the Republican Party have cheered on the lawsuit, in some cases filing formal friend-of-the-court briefs in support of it. They have also promised -- in op-eds, speeches and interviews -- to craft a transitional plan, or some kind of off-ramp , if the lawsuit is successful. The goals of such plans, Republican leaders have said, would be to minimize disruption for the people who now depend upon Affordable Care Act tax credits for their insurance, while crafting a long-term replacement scheme that would serve the public better than President Barack Obama s health care law has.

Rep. Paul Ryan (R-Wis.) was among those who made that promise back in early February, shortly after he took over as chairman of the Ways and Means Committee. We have to have a contingency plan, Ryan said. We think we need to have an option, a plan, for these states that might find themselves in this difficult position.

Ryans committee, arguably the most powerful in the House, has direct jurisdiction over health care financing. So how many hearings has it held about these contingency plans?

Zero.

And thats typical. Two other House committees, Education and the Workforce along with Energy and Commerce, have formal jurisdiction over health care financing. They havent held hearings, either.

Over in the Senate, Ron Johnson (R-Wis.) has introduced actual legislation and it has nearly 30 co-sponsors, including Mitch McConnell (R-Ky.), who is the majority leader. But the bill is at best a first draft at legislation and, so far, neither the Finance Committee (which has the most power over health legislation) nor the Health, Education, Labor and Pensions Committee (which also has some jurisdiction) has sought testimony or scheduled a hearing -- about either the Johnson bill specifically or, more generally, what to do if the Supreme Court stops the tax credits in those 34 states.

No, in the six months since the Supreme Court announced it would hear King v. Burwell, Republicans in Congress have held exactly one formal hearing that focused on the subject. It took place last week, before the Senate Small Business and Entrepreneurship Committee. But the Small Business Committee is among the least powerful in Congress and it has virtually no jurisdiction over health care financing issues. That may explain why it attracted very little interest -- even from committee members, only a handful of whom bothered to show up.

A generous takeaway from that hearing -- and lack of others -- is that Republicans are thinking about and working on health care plans much more intensely behind the scenes. Brendan Buck, Ryans spokesman, pointed out to The Huffington Post that Republican leaders have convened a working group to craft a post-King contingency plan -- with Ryan among its leaders. That group is now meeting three times a week, Buck said: Theyre informal, but its an active group.

In addition, several high-profile conservative intellectuals have been talking and writing actively about how Republicans ought to react if the court takes their side -- and what kind of health care plan Republicans should be proposing as an alternative to the Affordable Care Act, regardless of how the justices rule. Avik Roy , the Manhattan Institute scholar and Forbes columnist now working with former Texas Gov. Rick Perry s political action committee, has been outspoken on the need for an alternative. Philip Klein , longtime writer on health care and now managing editor of the Washington Examiner, has written a whole book on the subject.

But there's a reason that congressional Democrats spent literally years holding hearings on health care reform and then, in 2009, focusing intensely on legislation for several months. The hearings were sometimes acrimonious and, for reform advocates, the media coverage that testimony and questions generated was a source of never-ending grief. At the same time, these hearings, before the committees that actually had jurisdiction on the issues, were necessary to craft a solution that could accomplish the reforms main goals and then rally enough support to make it through Congress.

The kinds of plans Republicans seem to have in mind would require making equally difficult trade-offs and uniting even more fractious groups. Johnsons bill, for example, would limit enrollment in plans only to those who already have them, and it would eliminate the individual mandate -- the requirement that people get coverage or pay a fine -- in all of the states. That would force insurers to raise premiums or maybe exit markets altogether.

Other Republicans have discussed altering the Affordable Care Act's regulation on premiums, so that insurers could charge less to younger people. But reducing premiums for the young means raising them for the old, which might be hard for Republicans to pull off given that older voters are now their political base.

Meanwhile, the mere thought of extending Obamacare subsidies -- in any form, even temporarily -- will run into opposition from more conservative Republicans, particularly those in the House, who want a repeal and nothing more.

Johnson's bill has gone to the Congressional Budget Office for a formal estimate on its impact, a Johnson spokesperson confirmed. That's meaningful -- and more than can be said of most proposals that Republicans have floated on op-ed pages recently. But if Republicans were serious about crafting a proposal that's capable of avoiding disruption and passing Congress, they would have started hashing out these arguments months ago.

Of course, the absence of a public effort to match the public rhetoric matters only if Republicans are actually serious about passing a plan. They may not be. Their real goals may be purely cosmetic -- to insulate the party from a political backlash should millions of people suddenly lose health insurance and, more immediately, to ease the anxiety of Chief Justice John Roberts and Associate Justice Anthony Kennedy, either of whom might hesitate to issue a ruling with such potentially devastating consequences to so many people.

The lack of hearings obviously doesnt prove that Republican leaders have such ulterior, cynical motives. But it makes that theory a lot more plausible.