Congressional Republicans, despite pledging to quickly repeal the Affordable Care Act, are struggling with what parts of the law to roll back and how to lock up the votes they will need, particularly in the Senate, to push their ambitious plans.
Settling these questions may delay any major repeal vote for months. Just as importantly, a protracted debate could force President-elect Donald Trump and GOP lawmakers to preserve parts of the healthcare law they once swore to eliminate. And this all must be resolved before they even turn to the question of how to replace the law.
"Repeal is not going to be as simple as some people might have thought," said G. William Hoagland, a former Senate GOP budget official who is now senior vice president at the Bipartisan Policy Center.
"There are a number of Republicans, particularly in the Senate, who are going to be very nervous about voting to repeal something without knowing what this process may ultimately produce. … It could get a lot messier than people appreciate."
Amid the simmering internal GOP discussions, Trump has said very little about how he wants to approach repealing and replacing the healthcare law, though he has kept up his criticism. He called the law "lousy healthcare" on Tuesday.
Trump is sending Vice President-elect Mike Pence, a former member of Congress, to Capitol Hill on Wednesday to meet with House Republicans to discuss the planned repeal push.
Among other things, Republicans are still debating whether to scrap hundreds of billions of dollars in taxes that have helped extend health insurance to more than 20 million previously uncovered Americans, driving the nation's uninsured rate to historic lows.
That money is viewed as critical to paying for any replacement that Republicans ultimately may develop and has already prompted several GOP lawmakers to voice misgivings about eliminating the tax revenues.
Some in the GOP, particularly in state governments around the country, also are deeply concerned about rolling back federal aid that has allowed states to cover more low-income Americans through Medicaid.
Thirty-one states, including many with Republican governors, have expanded Medicaid through Obamacare and could lose billions of dollars if the law is cut back.
And in recent weeks, several state Republican leaders, including Arizona Gov. Doug Ducey and Montana House speaker Austin Knudsen, have voiced concerns about the loss of Medicaid coverage in their states.
In Washington, Republicans are also struggling to figure out what to do with Obamacare insurance marketplaces that Republicans worked for years to dismantle. In a reversal, GOP leaders now are trying to figure out how to prevent their collapse, which would jeopardize coverage for millions more Americans.
Insurance experts, including leading industry officials, have repeatedly warned Republicans over the past several months that repealing the health law without a replacement risks destabilizing insurance markets and will push many insurers to simply stop selling health plans.
On top of the uncertainty over repeal is the absence of a plan to actually replace Obamacare, a policy challenge that has stumped the GOP for more than six years and which Republicans now say will take years more to resolve.
That has made even many conservative health policy experts increasingly critical of the GOP legislative plan to repeal large parts of the law now while delaying a replacement.
"We do not support this approach to repealing and replacing the ACA because it carries too much risk of unnecessary disruption to the existing insurance arrangements upon which many people are now relying to finance their health services, and because it is unlikely to produce a coherent reform of healthcare in the United States," Joseph Antos and James Capretta of the American Enterprise Institute wrote in the journal Health Affairs.
Not long ago, GOP leaders were trumpeting their readiness to rapidly sweep the health law from the books.
"With a Republican president, there is a clear path to repealing Obamacare," House Speaker Paul Ryan (R-Wis.) said last January after congressional Republicans sent President Obama legislation that eliminated many of the healthcare law's key pillars.
That bill, which was crafted using budget rules that allow Republicans to circumvent filibusters in the Senate, was supposed to be the template for repeal.
It removed the unpopular insurance mandates in the law that require Americans to have health insurance or pay a fine, rolled back federal aid for Medicaid, scrapped federal insurance subsidies for low- and moderate-income consumers and eliminated a Medicare surtax on high-income households and other taxes on medical device makers and health insurance companies that fund the law.
To allow Republicans time to develop an alternative, the bill delayed implementation of the repeal for two years. (Obama vetoed the bill.)
Senior Republicans on Capitol Hill have said they still hope to send Trump a repeal bill early this year that largely parallels this approach.
Under the strategy being discussed, the House and Senate over the next couple weeks will pass what is known as a budget resolution that will direct Congress to develop a repeal bill through a process called budget reconciliation.
The House would then craft the repeal legislation, pass it and send it to the Senate. Under budget rules, Republicans, who have a 52-48 edge in the Senate, would need only a simple majority to pass the bill and send it to Trump.
But this approach is fueling an escalating criticism from healthcare groups representing doctors, hospitals and patients, including the American Diabetes Assn. and the advocacy arms of the American Cancer Society, which have warned that the GOP repeal strategy threatens insurance protections for tens of millions of Americans, beyond just those covered through Obamacare.
This week, four more leading physician groups — the American College of Physicians, the American Academy of Pediatrics, the American Academy of Family Physicians, and the American Congress of Obstetricians and Gynecologists — urged congressional leaders not to repeal the law without first developing a replacement.
"Enactment of such a 'repeal, delay and replace' bill … would create chaos in insurance markets, causing plans to pull out of the markets, with more than 7 million losing coverage in 2017 alone," Dr. Nitin S. Damle, president of the American College of Physicians, wrote in a letter to Senate leaders.
"Our commitment to ensuring that patients have access to affordable coverage and medical care obligates us to urge the Senate to vote no on the budget resolution," Damle wrote.