House Republicans' proposal to revise the Affordable Care Act in the US would lower the number of Americans with health insurance by 24 million while reducing the federal deficit by US$337 billion by 2026, congressional budget analysts said.

The report from the Congressional Budget Office underscores the dramatic loss in health insurance coverage that would take place if the GOP healthcare plan is enacted, potentially contradicting President Donald Trump's vow that the plan would provide "insurance for everybody" and threatening support from moderate Republican lawmakers.

Fourteen million people would lose health coverage next year alone, the report stated.

Premiums would be 15 to 20 per cent higher in the first year compared to the ACA, and 10 per cent lower on average after 2026.


Proponents of the plan, led by House Speaker Paul Ryan have argued that the total number of people covered is the wrong way to measure the law's impact.

The CBO report marks the beginning of a new phase in the debate over the week-old healthcare bill, which is moving through the House on an accelerated timetable despite opposition from Republicans, Democrats and virtually every sector of the US healthcare industry. Conservative Republicans, in particular, have demanded changes to the measure in exchange for their support.

The White House has spent the last week engaged in a charm offensive aimed at bringing those conservatives on board, as well as an effort to discredit the CBO before it released numbers that might cast the plan in a negative light.

"If you're looking to the CBO for accuracy, you're looking in the wrong place," White House spokesman Sean Spicer said last week.