The White House played down suggestions that the vote was delayed due to lack of support saying it would take place on Friday and would pass.
US lawmakers on Thursday delayed a vote on legislation to begin dismantling Obamacare as President Donald Trump and leaders in Congress laboured to find enough support among fellow Republicans for a new federal healthcare policy, report said.
The delay marked a setback for Trump, who is seeking his first major legislative victory and who campaigned on a promise to repeal and replace President Barack Obama's landmark law.
The US House of Representatives had been scheduled to vote on the bill on Thursday, but leaders put off the vote after failing to find enough support.
Failure to pass the American Health Care Act would cast doubt on Trump's ability to deliver other parts of his agenda that need the cooperation of the Republican-controlled Congress, including ambitious plans to overhaul the tax code and invest in infrastructure.
Conservatives and more moderate Republicans had opposing concerns about the bill, which is widely disliked by House Democrats.
Opposition Democrats have warned against repealing the former president's healthcare plan, saying it will leave tens of millions of Americans without access to affordable medical care.
Meanwhile US stocks declined modestly on Thursday with the market analysts saying that the delay could push back other pro-growth reforms that investors are hoping for, including tax cuts and deregulation.
"There is a concern that if the repeal and replace of the affordable care act takes long enough, we will not get tax reform this year and the market is trying to recalibrate that," said Art Hogan, chief market strategist at Wunderlich Securities.
"We'll see what happens next."
GOP: Hey guys let's spend 7 years promising Obamacare repeal, then choose one of these: (1) replacing it with the same crap; (2) leaving it.— Ben Shapiro (@benshapiro) March 23, 2017
International investors also are closely watching the activity. European markets closed higher, prior to the news the vote was pushed back and following Wednesday's largely upbeat US session.
The White House played down suggestions that the vote was delayed due to lack of support, with an administration official saying it would take place on Friday and would pass.