WASHINGTON ― Senate Republicans on Tuesday announced they plan to act quickly to strip away Obamacare’s funding while leaving elements of the program in place for two or three years.

The move would put them in lockstep with House Republicans, and would enable President-elect Donald Trump to sign a bill effectively repealing the program on his first day in office. Democrats promptly warned that the move would destabilize insurance markets in the short term and deprive millions of people of coverage in the long term, causing a “huge calamity” for America as well as for the Republican Party.

At a Capitol Hill press conference following a meeting with Vice President-elect Mike Pence, Senate Majority Leader Mitch McConnell (R-Ky.) stated that Obamacare repeal would be literally the first item of business when the new session begins.

“When we come back January 3, we’ll be moving to the Obamacare replacement resolution,” McConnell said. “The Obamacare repeal resolution will be the first item up in the new year.”

He made it clear that Republicans plan to proceed with the “repeal-and-delay” strategy that GOP leaders have been discussing publicly for the last few weeks.

Under such a strategy, Republicans would eliminate the Affordable Care Act’s funding using the budget “reconciliation” process, where Democrats can’t filibuster and where Republicans can thus proceed with a narrow majority. But the reconciliation bill would allow the money for Obamacare’s coverage expansion to flow for another two or three years.

In theory, this would give Republicans time to craft a replacement, while making sure the more than 20 million people now using Obamacare for coverage wouldn’t lose their insurance.

“What we intend to do by repealing Obamacare is to start to repair the damage that’s been done to families and businesses as a result of its enactment,” Sen. John Thune (R-S.D.) said. “And then, after we have done that, we will go about the process of replacing, in a step-by-step way, the Obamacare provisions that we think that cause the most damage, and put in place reforms that we think will really work.”

But experts have warned that quickly repealing the law, without an alternative system in place, would likely scare insurers away from the program, causing some markets to melt down. That’s particularly true if the repeal bill wipes away the individual mandate, a controversial Obamacare provision that forces people to pay a penalty if they decline to get coverage available to them. The aim of the mandate is to incentivize healthy people to buy coverage, so that insurers have enough premium dollars to offset the costs of the minority of beneficiaries with large medical bills.

Republican leaders say they can craft and enact a coverage scheme superior to Obamacare, but they’ve yet to agree on a detailed alternative ― even though they’ve been at it for six years. The plans in circulation now, which consist mostly of principles for reform rather than actual legislation, would all result in some combination of many fewer people insured and far weaker guarantees of coverage.

Typically these plans would mean cheaper insurance for the young and healthy, along with less government spending. But they’d also result in some combination of higher premiums or greater medical expenses for older and sicker people.

And even those plans may be more generous than what would eventually emerge from the legislative process likely to follow a repeal vote. That’s because repeal would immediately roll back Obamacare’s taxes, which consist primarily of fees on the health care industry and new levies on the wealthiest 3 percent of Americans.

It would be a windfall for industries, and for those wealthy taxpayers. But without that revenue in place, crafting an alternative scheme to provide anything resembling comparable coverage would be politically difficult, if not impossible.

At the press conference, Thune gave a list of principles that would guide Senate Republicans as they contemplate alternatives to Obamacare, including more power for states, greater competition and providing relief to small businesses.

Conspicuously absent from the list was any information about the number of people who would have insurance when Republicans were done, or what quality coverage they would have.

Thune and the other Republican leaders went on to express hope that Democrats would join them in this effort ― and, to enact the kind of reforms they have in mind, they would almost surely need at least some Democratic support. That’s because a bill repealing Obamacare’s insurance regulations and imposing new changes couldn’t pass through reconciliation. It would have to go through the regular legislative order, which would be subject to Democratic filibusters.

But Democrats, mindful of how Senate Republicans unified against virtually every major proposal of the Obama years, seem in no mood to help. Instead, at a press conference of their own Tuesday, they warned that repealing the law without an alternative in place would be reckless, that it would cause immediate harm and that promises of a “better way” to bolster health care access were meaningless.

“They have nothing to put in its place,” Sen. Charles Schumer (D-N.Y.), the incoming minority leader, said. “And believe me, just repealing Obamacare, even though they have nothing to put in its place, and saying they’ll do it sometime down the road, will cause huge calamity, from one end of America to the other. They don’t know what to do. They’re like the dog that caught the bus.”

Schumer also predicted that Republicans would face dire political consequences as a result of their plan.

“To our Republican friends across the aisle,” he said, “bring it on.”