President Donald Trump faced a titanic showdown in Congress later today with a crucial vote to repeal and replace Obamacare hanging in the balance and too close to call.
In a high stakes gamble Mr Trump issued a take-it-or-leave-it ultimatum to rebel Republicans, indicating that if the measure fails he will leave Obamacare in place and move on to other priorities.
Mr Trump was said to be "agitated" by the reluctance of conservative Republican congressmen to vote for the American Health Care Act because they do not believe it goes far enough in dismantling Obamacare.
Republicans have a majority in the House of Representatives but they can only afford to lose 21 votes from their own side. Democrats will all vote against the bill..
However, with only hours to go before an expected vote at least 35 Republicans still planned to vote against, despite last minute concessions from Mr Trump and his allies.
Defeat would be a huge setback to Mr Trump instilling doubts about his ability to carry his own party with him in Congress not only on healthcare but other major platforms of his campaign like tax reform and infrastructure investment. Global financial markets were monitoring the vote closely.
Some Trump supporters were already privately blaming any failure of the bill on Paul Ryan, the House Speaker, who has shepherded it in Congress.
Mr Ryan said: "For seven and a half years we have been promising the American people that we will repeal and replace this broken law because it's collapsing and it's failing families, and tomorrow we're proceeding."
Tweeting from the presidential account, Mr Trump said: "Disastrous #Obamacare has led to higher costs & fewer options. It will only continue to get worse! We must #RepealANDReplace."
The promise to repeal Obamacare was key to Republicans keeping control of Congress, and to winning the White House, in November's election.
The bill has been held up by members of the Freedom Caucus, a conservative group of Republican politicians. Congressman Mark Meadows, chairman of the Freedom Caucus, said there was "No deal" with the Republican leadership.
Mr Meadows said he was still a "No" vote and he had told Mr Trump personally. But he praised Mr Trump, saying: "The engagement of the president (on this) is unparalleled in the history of our country. The Freedom Caucus is committed to working with the president to get this done."
He said the key issue at stake was "does this bill reduce premiums enough" for Americans paying for health insurance
But he said "progress was being made" and the Freedom Caucus was "really trying to get to yes" while Mr Trump had made some "good faith gestures to get the ball rolling".
He said Thursday night, the seventh anniversary of former president Barack Obama signing his Affordable Care Act into law, had been an "artificial deadline imposed on ourselves" for repealing it.
An extra 20 million people gained health insurance under Obamacare. The Republican healthcare bill would halt Mr Obama's tax penalties against people who refuse to pay for insurance and cut government financial assistance for the poor, instead providing tax credits.
It keeps some parts of Obamacare, including forcing insurers to accept people with pre-existing conditions, but members of the Freedom Caucus, and many Americans who voted for Mr Trump, wanted wholesale repeal.
Mr Trump issued a rallying cry to his millions of followers on Twitter to phone the offices of their congressmen and demand they vote for the bill.
In a last minute attempt to save his flagship healthcare reform Mr Obama said: "This fight was about more than healthcare, it was about the character of our country. This fight is still about all that today."