Its Obamacare replacement season! Or at least, thats what congressional Republicans want people to believe.

Nearly five years after the Affordable Care Act became law and two years into its expansion of health coverage to an estimated 10 million uninsured people , GOP lawmakers are renewing their so-far fruitless efforts to develop a health reform plan they can position as a replacement for President Barack Obama s health care law.

Its no coincidence that this is taking place in the run-up to a June Supreme Court ruling that could blow a giant hole in the Affordable Care Act . A decision against Obamacare would kick millions of people , mainly living in red states , off their health plans -- and leave them looking to the Republican Congress for a solution.

Congressional Republicans want Americans -- especially the nine on the Supreme Court -- to think the GOP can do in less than five months what it took Democrats decades to achieve: enact comprehensive health care reform legislation. But given that Republicans have been unable to reach consensus on much beyond repealing Obamacare in the last five years, thats an ambitious timeline.

This pattern has been repeating itself since 2009 . Just this week, House Republicans approved yet another bill to repeal the Affordable Care Act, and this one included language charging three House committee chairmen with devising a replacement plan.

Meanwhile, Senate Finance Committee Chair Orrin Hatch (Utah), Sen. Richard Burr (N.C.) and House Energy and Commerce Committee Chairman Fred Upton (Mich.) unveiled the GOP's latest attempt to construct an Obamacare alternative on Wednesday.

Even though the proposal is virtually identical to the one that Hatch and Burr issued a year ago with then-Sen. Tom Coburn (R-Okla.), the duo -- along with Upton -- scored headlines describing their framework as the Obamacare replacement plan. But remarks from House Speaker John Boehner (R-Ohio) on Thursday underscore how far congressional Republicans are from having an actual alternative in place.

Clearly, our three chairmen have an awful lot of work to do to come up with our replacement. But I would expect all of this to be part of the discussion -- all of it. Listen, theres a lot of ideas out there," Boehner said. "The key is going to be to boil those concepts down to what a real replacement would look like."

That wont be easy .

The Hatch-Burr-Upton proposal is a case study in the difficult trade-offs Republicans would eventually have to negotiate among their members and supporters -- and then defend to the broader public. Relative to Obamacare, the Republican proposal would provide financial assistance to fewer people and cut off aid at a lower income level. It would also roll back Obamacares Medicaid expansion, replacing it with a tax credit for buying private insurance; eliminate regulations that guarantee all policies include comprehensive benefits; and, among other things, give insurers more leeway to vary premiums by age.

Republicans promote these changes as increasing choice and flexibility in insurance, claiming that they will result in less federal spending and that younger adults will pay lower prices.

But each of these proposed changes would carry other consequences as well. Policies without full benefits, including junk plans and mini-med policies, would return to the market. The same pricing practices that reduced premiums for 25-year-olds would jack them up for 60-year-olds, putting insurance out of reach for many older Americans.

The proposals precise effect on the uninsured is hard to tell, but under the prevailing assumptions of most forecasting models -- including those used by the Congressional Budget Office -- the likely impact would be more people without insurance and/or much weaker financial protection, as an analysis of last years plan by the Center on Budget and Policy Priorities suggested.

Republicans might have a hard time defending those changes -- particularly when so many of their constituents now benefit from the Affordable Care Acts more generous assistance and protections. Yet for more conservative Republicans who are bent on full repeal and resistant to increased federal authority over the health care system, the proposal might actually not go far enough. (Last years plan drew fire from the right for precisely that reason.)

Indeed, the GOP is far from agreement on the question of whether Congress should replace Obamacare with anything at all, in the event the law is repealed legislatively or gutted by the Supreme Court . As a general rule, expanding access to health care reform requires enacting redistributive tax and social welfare policies -- the kind many conservatives oppose on principle.

To date, none of the GOP health care reform proposals have so much as made it out of committee. And no Republican in Congress has laid out a plan for advancing any health care bills through the legislative process this year. In 2013, then-House Majority Leader Eric Cantor (R-Va.) couldnt even get a comparatively modest bill funding high-risk pool insurance programs for sick people passed, thanks to a conservative revolt.

This week, Sen. Lamar Alexander (R-Tenn.), who chairs the Health, Education, Labor and Pensions Committee, acknowledged to Politico that Republicans might choose not to come together on a plan at all .

Perhaps Alexander realizes that putting together a real Obamacare alternative will take more time -- and more genuine interest -- than Republicans have, or than the Supreme Court's schedule demands.

Sabrina Siddiqui contributed reporting.