With four Republicans now lined up against Senate Majority Leader Mitch McConnell's health overhaul, the plan has flatlined in the 100-member chamber, where the party could afford only two defectors in order to get the measure passed.
McConnell announced a fresh effort aimed at repealing the Affordable Care Act now and crafting a replacement later, but that, too, ran into opposition from at least three Republicans who refused to repeal the law without a suitable fix at the ready.
The dramatic implosion effectively means Trump, who marks his first six months in office later this week, has no major legislative victory under his belt, squandering months of political capital.
Trump fired off a series of early morning tweets complaining about how he was "let down" by Democrats "and a few Republicans," who announced their opposition to the leadership plan to repeal and replace the 2010 Affordable Care Act, also known as Obamacare.
Trump had campaigned relentlessly on a pledge to abolish most of the ACA, proclaiming at an October campaign rally that it would be "so easy" to immediately repeal and replace the law.
But on Monday night he ran into the uncompromising reality of American politics: even with a president's party enjoying a majority in both chambers, crafting and passing landmark legislation can be perilous in the US Congress.
The failure suggests an inability by Trump - a political neophyte who often highlighted his lack of connections to establishment Washington - to get members of his own party to fall into line.
Trump put on a brave face, insisting on Twitter that "we will return!"
But later Tuesday at the White House Trump said he was "disappointed" about the roadblock and that now it would be easier to just "let Obamacare fail."
He also stressed he wanted nothing to do with the blame for the collapse.
"We're not going to own it. I'm not going to own it. I can tell you the Republicans are not going to own it," he said.
"We'll let Obamacare fail and then the Democrats are going to come to us" looking to work on a solution.
The president was also eager to claw back some of the Republicans who had opposed the plans, leaving open the prospect of another effort later this year, and urged Republicans to do better at the ballot box in 2018 in order to have a larger Senate majority.
'Time to start over'
McConnell told colleagues Tuesday that despite feeling "regret" that the effort failed, he planned in coming days to introduce a bill that repeals Obamacare outright, but with a two-year delay of implementation, in order to allow Congress time to craft a replacement.
A straight repeal bill passed Congress in 2015. That was during Obama's presidency, and Republicans knew they would pay no political price for their votes, as Obama vetoed the measure.
The White House has said Trump would sign such legislation, putting Republicans on the hook for any ensuing disruption to the health care system.
Two years ago, the nonpartisan Congressional Budget Office warned that simply repealing Obamacare would essentially kick 18 million people off health care in the first year compared to current law, a figure that would balloon to 32 million by 2026.
That is far above the 22 million that CBO forecast would lose coverage under the latest repeal-and-replace legislation.
With a number of Senate Republican moderates voicing concern about how the latest bill could adversely impact millions of people insured through Medicaid, the health coverage program for the poor and the disabled, it appeared unlikely that McConnell's repeal bid would win enough support.
Three Senate Republicans have already declared opposition to the repeal-only plan, including Shelley Moore Capito of West Virginia, where significant numbers of residents are on Medicaid.
"I can not vote to repeal Obamacare without a replacement plan that addresses my concerns and the needs of West Virginians," she said in a statement.
Several other Republicans have expressed concern not only about the plan's potential impact on millions of families, but on the secretive nature of the drafting process.
While Democrats celebrated, Senate Minority Leader Chuck Schumer extended an olive branch to his Republican rivals.
"It's time to move on. It's time to start over" on health care, he said.
Schumer called on Republicans to "work with Democrats on a bill that lowers premiums, provides longterm stability to the markets and improve our health care system."
Meanwhile Vice President Mike Pence shuttled up to Capitol Hill to huddle with Republicans amid confusion over the next step.
"I have no idea what the game plan is quite honestly," an exasperated Senator Ron Johnson told reporters. "It's an insane process."
