WASHINGTON - Two more US Republican senators announced their opposition Monday to their party's efforts to revamp Obamacare, derailing the controversial legislation in its current form and potentially dealing a monumental setback to President Donald Trump.
Republican leaders are desperate for a major legislative victory this year - and keen to fulfil Trump's campaign pledge to dismantle the 2010 health care reforms of his predecessor Barack Obama, formally called the Affordable Care Act.
But they had no votes to spare.
Republicans control 52 of the chamber's 100 seats. Democrats are united against the controversial legislation, while Republicans Susan Collins and Rand Paul declared their opposition last week.
So when Senate conservatives Mike Lee and Jerry Moran announced late Monday they could not support the bill, the news sent shockwaves across Washington.
"We should not put our stamp of approval on bad policy," Moran - who faced considerable opposition at home in Kansas to the measure - said in a statement, adding that the new bill "fails to repeal the Affordable Care Act or address health care's rising costs."
For Lee, "in addition to not repealing all of the Obamacare taxes, it doesn't go far enough in lowering premiums for middle class families; nor does it create enough free space from the most costly Obamacare regulations."
Their defections mean that the bill has no chance of even getting a vote on the Senate floor unless Senate Majority Leader Mitch McConnell decides to make significant changes to woo skeptics back into the fold.
"Republicans should just REPEAL failing ObamaCare now & work on a new Healthcare Plan that will start from a clean slate. Dems will join in!" Trump tweeted after Lee and Moran made their opposition known.
Over the weekend, McConnell delayed a vote to proceed on the bill, after Senator John McCain, 80, underwent surgery to remove a blood clot above his eye and said he would recuperate at home in Arizona for at least a week.
But McCain's absence is now something of a moot point.
Several Republicans had already expressed concern that the new bill could slash funding for Medicaid, the health insurance programme for the poor and the disabled.
The new bill would gradually roll back the programme, a move that some Republicans warn could lead to millions losing coverage.
The latest defections also show that conservatives are frustrated that the new bill does not repeal the Obamacare taxes.
As Republicans grappled with the collapse - the second major stumble on the legislation in a mont - Democratic reaction was swift.
"This second failure of Trumpcare is proof positive that the core of this bill is unworkable," said top Senate Democrat Chuck Schumer.
"Rather than repeating the same failed, partisan process yet again, Republicans should start from scratch and work with Democrats on a bill that lowers premiums, provides long-term stability to the markets and improves our health care system." .
'Wheels off the bus'
Republican leaders are eager to notch a major victory for Trump in Congress as he nears the six-month mark of his presidency later this week, but health care is now unlikely to be that achievement.
And while tax reform and infrastructure are also high priorities that Congress could address, they will need to take a back seat for now to a logjam of must-finish business in the Senate, including consideration of raising the limit on federal borrowing.
Some fear that repealing Obamacare could adversely impact millions of Americans on Medicaid, or make health costs soar for people with pre-existing conditions.
There is little institutional support for the bill, and even less for an amendment introduced by Senator Ted Cruz that would allow insurers to offer bare-bones plans that do not comply with Obamacare's coverage requirements.
The chief executives of America's Health Insurance Plans and the Blue Cross Blue Shield Association called it "simply unworkable in any form." A Post poll released Sunday showed Americans preferred Obamacare to the Republican plan by 50 per cent to 24 per cent.
Despite the Republican setback, Democratic Senator Chris Murphy said his rivals will take another bite at the health care apple.
"There's a couple wheels off the bus right now," Murphy told MSNBC after the announcement from Lee and Moran.
But "they are not going to give up on it," he added.