"For years, they've been talking about repeal-replace, repeal-replace," Trump says.
Top US Senate Republican Mitch McConnell will try to pull a political rabbit out of his hat Thursday when he unveils a revamped health care bill, after unpopular earlier versions frustrated conservatives and moderates in his party.
With opposition growing, and McConnell postponing the Senate's August recess by two weeks to allow more time to bring skeptical lawmakers on board and salvage Donald Trump's top legislative priority, the president used his bully pulpit to urge fellow Republicans to rally round the effort.
He warned in a Wednesday interview with the Christian Broadcasting Network that he would be "very angry" if Congress failed to pass legislation which repeals and replaces large parts of Obamacare, the health reforms of his predecessor Barack Obama.
"For years, they've been talking about repeal-replace, repeal-replace," Trump said. "They have to do it. They have to get together and get it done."
With Democrats united in opposition, McConnell needs support from at least 50 of the Senate's 52 Republicans to pass the measure in the 100-member chamber.
Ten Republicans have said they will not support the bill as written. The test is whether leadership can convince most of them to get on board.
"I will be very angry about it" if the bill collapses, Trump said. "I'm sitting waiting for that bill to come to my desk. I hope that they do it."
Polls show the previous version to be widely unpopular. An analysis by the non-profit Congressional Budget Office forecast that under the bill, ranks of the uninsured would swell by 22 million people by 2026 compared to current law.
McConnell's intent is to roll out the revised measure Thursday, most likely at a Republican caucus meeting set for 11:30 am (1530 GMT).
He then wants to receive a CBO score on the new version as early as next Monday, and hold a vote to begin debate on the bill next week.
The plan scoffed at by several Senate Republicans would keep parts of Obamacare intact, but strip away much of its funding. It also rolls back the expansion of Medicaid, the federal health care program for the poor and disabled.
Conservatives say they want a bill that is less like Obamacare, and that cancels all of the law's taxes.
Republican centrists fear that slashing Medicaid funding by more than $700 billion could devastate millions of families.
One option under consideration is an amendment by Senator Ted Cruz that would allow insurers to offer cheaper plans that do not cover many of the health services required under current law.
But some Republicans warn that move could end up abolishing protections for people with pre-existing conditions and send costs soaring for children and older insurance holders in the individual market.
Top Democrat Senator Chuck Schumer called on Republicans to abandon the plan and "start over," working together to shore up Obamacare.
"When you have a rotten product, time is not on your side," Schumer told colleagues.