WASHINGTON — The Republican Party's long-promised repeal of “ObamaCare” stands in limbo after Senate GOP leaders, short of support, abruptly shelved a vote on legislation to fulfill the promise.

The surprise development leaves the legislation's fate uncertain while raising new doubts about whether President Donald Trump will ever make good on his many promises to erase his predecessor's signature legislative achievement.

Senate Republican leader Mitch McConnell announced the delay Tuesday after it became clear the votes weren't there to advance the legislation past key procedural hurdles. Trump immediately invited Senate Republicans to the White House, but the message he delivered to them before reporters were ushered out of the room was not entirely hopeful.

“This will be great if we get it done, and if we don't get it done it's just going to be something that we're not going to like, and that's OK and I understand that very well,” he told the senators, who surrounded him at tables arranged in a giant square in the East Room. Most wore grim expressions.

In the private meeting that followed, said Sen. Marco Rubio of Florida, the president spoke of “the costs of failure, what it would mean to not get it done — the view that we would wind up in a situation where the markets will collapse and Republicans will be blamed for it and then potentially have to fight off an effort to expand to single payer at some point.”

The bill has many critics and few outspoken fans on Capitol Hill, and prospects for changing that are uncertain. McConnell promised to revisit the legislation after Congress' July 4 recess.

“It's a big complicated subject, we've got a lot discussions going on, and we're still optimistic we're going to get there,” the Kentucky lawmaker said.

But adjustments to placate conservatives, who want the legislation to be more stringent, only push away moderates who think its current limits — on Medicaid for example — are too strong.

In the folksy analysis of John Cornyn of Texas, the Senate GOP vote-counter: “Every time you get one bullfrog in the wheelbarrow, another one jumps out.”

McConnell can lose only two senators from his 52-member caucus and still pass the bill, with Vice President Mike Pence to cast a tie-breaking vote. Democrats are opposed, as are most medical groups and the AARP, though the U.S. Chamber of Commerce supports the bill.

A number of GOP governors oppose the legislation, especially in states that have expanded the Medicaid program for the poor under former President Barack Obama's Affordable Care Act. Opposition from Nevada's popular Republican Gov. Brian Sandoval helped push GOP Sen. Dean Heller, who is vulnerable in next year's midterms, to denounce the legislation last Friday.