President Donald Trump has declared Obamacare "dead" after the Republican healthcare bill was narrowly passed by the lower chamber of Congress.
The 217-213 vote marked his first legislative victory and goes some way to keeping a key campaign promise to roll back his predecessor's law.
Democrats say the American Health Care Act will leave millions uninsured.
The bill now heads to the Senate, where Republicans have indicated they will cast it aside and write a new law.
Protesters shouted "Shame on you!" as lawmakers left Capitol Hill after the knife-edge vote.
But there were celebrations moments later on the White House lawn, where the president laid on a reception for Republicans in the House of Representatives.
Six weeks ago, their healthcare attempts appeared doomed when they did not have enough support to have a vote.
But that bill has undergone several revisions to satisfy both the conservative and moderate wings of the Republican party.
"Make no mistake, this is a repeal," said a triumphant Mr Trump in the Rose Garden. Obamacare, he added, was "essentially dead".
"Premiums will be coming down, deductibles will be coming down, but very importantly it's a great plan."
What changed since March?
One amendment added since then to placate conservatives means states can opt out of providing essential benefits such as cancer treatment and emergency room visits.
And when $8bn over five years was thrown in towards coverage for sick people who otherwise might face higher costs, several moderate Republicans changed course and backed it.
About 20 million Americans gained healthcare coverage under President Barack Obama's 2010 Affordable Care Act, but Republicans viewed it as an overreach of the federal government and said patients had less choice and higher premiums.
The New York attorney general said on Thursday evening that he would challenge the bill in court if it became law, on the basis that it would deny people access to care.
What happens now?
The bill, if it becomes law, would mark a major overhaul in the US health system.
But key elements could be ditched by Republican senators, who have said they will start fresh.
Republican Senator Lisa Murkowski said she would like "a clean slate", while Senator Bob Corker said the current bill has "zero" chance in the Senate.
The party controls the chamber 52-48, meaning it can lose no more than two Republicans in order for it to pass.
If the Senate passes its own bill, the plan then goes back to the House for approval or more negotiations and amendments.
(Published by BBC - May 4, 2017)