The Republican Party, for the first time ever, has a very real shot at repealing Obamacare — and leaving tens of millions of Americans without health insurance coverage.

Donald Trump has won the White House. Republicans retained control of the Senate, and they’re expected to keep the House, too. One party rule means that President Obama’s health care law is in real jeopardy.

“They have a death blow to the Obamacare health coverage expansion,” says John McDonough, a Harvard University professor who worked in the Senate on the passage of the Affordable Care Act.

Republicans began to lay serious groundwork against Obamacare last winter. In January, both the Senate and the House passed a reconciliation bill that took apart Obamacare’s expansion of Medicaid and private, subsidized health insurance.

The bill didn’t matter much at the time — Obama repealed it when it arrived at his desk — but it showed that Republicans could use the reconciliation process to take apart key Obamacare pillars, requiring a simple majority rather than the 60 votes needed to overcome a filibuster.

Trump has promised that repealing Obamacare would be his first act in office. All he needs to do is pull this ready-made Republican plan off the shelf.

Republicans have already mapped out how to repeal Obamacare with a simple majority in the Senate

Most Senate bills need 60 votes to overcome a filibuster. But Senate rules also allow bills to pass with a simple majority if they only relate to spending, a process known as reconciliation. Reconciliation bills need to be approved by a parliamentarian, who certifies that the content does indeed have budgetary impact.

Last winter, Republicans drafted a bill that would fit the parameters of the reconciliation process. HR 3762 was introduced into the House on October 16, 2015, by Rep. Tom Price (R-GA). The bill would repeal Obamacare’s tax credits for low- and middle-income Americans to purchase insurance at the end of 2017. It would end the Affordable Care Act’s Medicaid expansion at the same time, essentially creating a two-year transition period in which Republicans would presumably consider Obamacare replacement plans.

“Practically, you can’t turn everything off immediately,” says Chris Condeluci, who worked as tax and benefits counsel for the Senate Finance Committee's Republicans during the Affordable Care Act debate. “The GOP doesn’t want to get beat up over kicking 20 million people off of insurance.”

HR 3762 would also repeal Obamacare’s mandate. It would end many of Obamacare’s major taxes that helped pay for the health law’s insurance expansion.

This includes taxes on health insurers, hospitals, and medical device manufacturers and a Medicare payroll tax of 0.9 percent that the law levied on Americans who earn more than $200,000 (or $250,000 for a married couple).

The Congressional Budget Office estimates that 22 million people would lose insurance under this plan after the two-year transition policy ended. These would mostly be people who have coverage through Medicaid and the insurance marketplaces.

The repeal plan would reduce the deficit by between $281 billion and $193 billion, depending on how CBO measures the economic effects of the legislation.

House Republicans passed HR 3762 on October 23, 2015, and the Senate followed on December 3, 2015. President Obama vetoed the bill when it came to his desk, and the bill was covered as yet another failed Republican attempt to repeal Obamacare.

But as McDonough recounts, it was arguably much more.

“People laughed about why would Republicans pass another repeal vote that Obama would veto,” he says. “I wasn’t laughing. It took significant unity to get this through Congress.”

Republicans have a strong Obamacare repeal plan. They don’t have a strong Obamacare replace plan.

HR 3762 does thorough work demolishing Obamacare’s insurance expansion. But it also leaves millions without health insurance unless Republicans also pass a replacement plan.

Right now that replacement plan isn’t really fleshed out. Condeluci, who worked in the Senate during the Obamacare debate, expects that Republicans would use the two-year transition window to come up with a replacement — but that they’d pass this initial reconciliation bill before that.

“I don’t think the two [repeal and replace] would come in tandem,” Condeluci says. “Replace needs to be litigated to a greater degree than it has before.”

House Republicans did publish a document outlining their Obamacare replacement plan this summer, called “A Better Way.” It envisions many health policy proposals that have become common in conservative plans, like block-granting Medicaid and allowing insurance sales across state lines.

But as Condeluci points out, that paper “isn’t in legislative form, and the Senate hasn’t weighed in.”

Trump does have a health policy proposal, but it is still a relatively sparse, bullet-pointed list on his website. “I would envision Trump looking to Congress to drive the replace process, just as the Obama administration did with the Affordable Care Act,” Condeluci says.

Republicans have promised dozens of times to repeal Obamacare. Will they actually follow through?

Repealing Obamacare would undeniably lead to millions of Americans losing insurance coverage — many who had gained coverage for the first time as the law ended preexisting conditions and expanded Medicaid to cover more low-income Americans.

And Trump has repeatedly promised throughout his campaign that he is committed to covering everybody.

"I am going to take care of everybody," he told 60 Minutes in an interview last fall. "I don’t care if it costs me votes or not. Everybody’s going to be taken care of much better than they’re taken care of now."

Trump’s health care website promises that he will “not allow people to die on the sidewalks and the streets of our country" for lack of access to health insurance.

At the same time, Trump, like the majority of Republicans, has repeatedly called to repeal Obamacare.

"If we don't repeal and replace Obamacare, we will destroy American health care forever,” Trump said at his Pennsylvania rally last week.

He called the law a “catastrophe” and lamented how deductibles could go “up to $15,000.” Meanwhile, he promised to deliver “quality, reliable, affordable health care.”

It is a moment of reckoning for Trump and other Republicans — whether they will follow through on the calls for Obamacare repeal that they have made consistently for six years, or whether they will back off at the prospect of causing millions to lose insurance coverage.

“The fly in the ointment is that some of the Republicans supported the reconciliation repeal thinking it would never happen,” says McDonough. “Will they actually vote to take away insurance from 20 million Americans? That’s the unknown right now.”

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