Obamacare, the fruit of an eight-year drive to extend medical coverage to tens of millions of Americans, will come under sustained assault when Trump takes office on January 20 with Republican majorities in both chambers of Congress.
But the debate over US health care began in earnest Wednesday at the highest levels, with Obama and Vice President-elect Mike Pence making duelling visits to Capitol Hill to urge their legislative foot soldiers to gird for battle.
"I envy you for the opportunity you are going to have to engage in this fight to protect health care for the American people," the outgoing president told Senate and House Democrats, according to Senator Ed Markey, who attended the 100-minute meeting.
After a crushing election loss, Democrats may have limited options for stalling a repeal of Obamacare without significant Republican defections.
They also face criticism that Obama's reforms have led to rising insurance premiums and a string of technical problems.
But certain elements of Obamacare remain popular, notably the provisions barring companies from refusing coverage due to pre-existing conditions and allowing children to retain coverage on family plans through age 26.
Repeal and then what?
Republican opposition in general to Obamacare is clear -- "They broke the health care system," House Speaker Paul Ryan said of Obama's administration -- but his party's prescription to fix it is not.
Ryan has proposed a tax credit system as a possible replacement, but the costs to government and individuals remain vague.
The White House is betting that American voters will revolt if Trump moves to strip millions of their coverage with no viable alternative -- forcing the incoming president to confront the most radical reformers within his own party.
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While Pence addressed the issue gingerly in Congress, he stressed that Trump would make the process of repealing the Affordable Care Act one of the administration's top priorities.
"The first order of business is to repeal and replace Obamacare," Pence told reporters in the US Capitol shortly after meeting with House Republicans.
But Trump himself cautioned against over-hasty action.
"Republicans must be careful in that the Dems own the failed ObamaCare disaster," the president-elect said on Twitter, warning Republicans to allow it to "fall of its own weight."
While urging a full repeal of the law, Ryan also said Republicans should avoid putting millions of families in further financial jeopardy by gutting Obamacare without a viable alternative in place.
"We've got to fix this by replacing it with something better. In that transition, we want to make sure we don't pull the rug out from anybody," he said.
One Republican lawmaker, Chris Collins, said the party was looking at a six-month timeline for crafting an Obamacare alternative. Other Republicans said that was far too ambitious.
Senator John McCain expressed confidence that fellow Republicans would be able to forge a replacement plan to go along with legislative repeal action.
"We'll be doing both," McCain said. "We'll know what the replacement is."
Senate Majority Leader Mitch McConnell, who has already launched the legislative process for repeal, welcomed Pence to lunch with all Senate Republicans after his House huddle.
Pence, addressing reporters afterward, provided no details on the replacement plan being crafted by his party.
But "the architecture of the replacement of Obamacare will come together, as it should, through the legislative process in the weeks and months ahead," he said.
'A little queasy'
Republican legislators are eager to take charge after eight years spent fighting against Obama's policies.
But some are wary that white working-class Americans, who helped send them to office, may bear the brunt of any reforms.
Dismantling Obamacare could also have knock-on effects for funding health care for retirees, a group essential to the Republican Party's survival.
In these two issues, Democrats see pressure points they hope to exploit in defense of Obama's plan.
"It's not surprising to me that there are some Republicans who are now a little queasy about the prospect of the impact that repealing Obamacare would have on their own supporters," said White House spokesman Josh Earnest.
"We know there are people all across the country who benefit from this law, who are protected by this law, whose lives have been saved by this law."
Democratic leaders voiced support for a stiff defense of the Affordable Care Act in the face of Republican attacks.
"Instead of working to further ensure affordable care for all Americans, they seek to rip health care away from millions of Americans, creating chaos in our entire economy," charged Senate Democratic leader Chuck Schumer
