Two more Republican senators have said they oppose their party’s replacement for President Obama’s health system, making it impossible for the bill to pass in its current form, BBC report.
Mike Lee and Jerry Moran say the new legislation does not go far enough in repealing the health legislation.
Republicans have been divided on the issue, with moderates concerned about the effects on the most vulnerable.
President Donald Trump made repealing Obamacare a key campaign pledge.
“Regretfully, it is now apparent that the effort to repeal and immediately replace the failure of Obamacare will not be successful,” Senate Majority Leader Mitch McConnell said.
The Republican plan had kept key Obamacare taxes on the wealthy, while allowing insurers to offer less coverage and imposing sharp cuts to healthcare for the poor.
With the two new opponents, Republicans – who hold 52 seats – no longer have enough votes to pass the bill in the 100-member Senate.
The two senators simultaneously announced their opposition to the planned reforms, joining senators Rand Paul and Susan Collins, who were also against the bill.
Mr Moran said “we should not put our stamp of approval on bad policy” while for Mr Lee, “in addition to not repealing all of the Obamacare taxes [the bill] 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.”
Reacting to what is being seen as a significant setback, Mr Trump urged Republicans to repeal the “failing Obamacare now and work on a new healthcare plan that will start from a clean slate”.