The US Senate will "defer" its work on repealing and replacing Obamacare as senior lawmaker John McCain recovers from surgery to remove a blood clot above his eye, the chamber's Republican leader announced late Saturday.
The health care reform bill, a central campaign pledge by President Donald Trump and many of his fellow Republicans, has already neared collapse, with two Republicans publicly opposing it. It would likely fail without McCain's vote.
"There are few people tougher than my friend John McCain, and I know he'll be back with us soon," Republican Majority Leader Mitch McConnell said in a statement wishing the senior Arizona lawmaker well.
"While John is recovering, the Senate will continue our work on legislative items and nominations, and will defer consideration of the Better Care Act."
The Mayo Clinic, which performed the surgery Friday in Phoenix, said the five-centimeter (two-inch) blood clot was "successfully removed" from above his left eye during a "minimally invasive" craniotomy with an eyebrow incision.
Tissue pathology reports are due in the coming days.
McCain's office said the lawmaker, "in good spirits and recovering comfortably at home with his family," would recover in Arizona through next week.
Achieving Trump's goal to end predecessor Barack Obama's 2010 sweeping reforms has been elusive in the first six months of the new administration.
Several Republicans in the party's conservative and moderate wings have expressed deep concerns over the latest draft unveiled Thursday.
Some fear that repealing the Affordable Care Act -- the formal name of Obamacare -- could adversely impact millions of Americans by effectively forcing them off of Medicaid, the health insurance program for the poor and the disabled, or making health costs soar for people with pre-existing conditions.
With Democrats united in opposition, McConnell needs support from at least 50 out of 52 Republicans to pass the measure in the 100-member chamber. In the event of a 50-50 split, Vice President Mike Pence would cast the tie-breaking vote.