Fourteen million Americans would lose medical insurance by next year under a Republican plan to dismantle Obamacare that would also reduce the budget deficit, the nonpartisan US Congressional Budget Office says.
The CBO report, which also dealt a potential setback to President Donald Trump's first major legislative initiative, forecast that 24 million more people would be uninsured in 2026 if the plan being considered in the House of Representatives were adopted. Obamacare expanded insurance to about 20 million Americans.
The report could influence sentiment toward a bill already under fire from Democrats and some Republicans, who have long vowed to repeal the 2010 Affordable Care Act, former Democratic President Barack Obama's signature piece of domestic policy.
WATCH: White House denies health care impact
The CBO projected that 52 million people would be uninsured by 2026 if the bill became law, compared with 28 million who would not have coverage that year if the law remained unchanged.
Two House of Representatives committees have approved the legislation to dismantle Obamacare that was unveiled by Republican leaders a week ago, but it faces opposition from not only Democrats but also medical providers including doctors and hospitals and many conservatives. The CBO report's findings could make the Republican plan a harder sell for legislators, particularly in the US Senate.
The agency, however, said federal deficits would fall by $US337 billion ($A445 billion) between 2017 and 2026 under the Republican bill.
Some health policy experts and Wall Street analysts said the report was more draconian than expected, with the uninsured rate declining more quickly than foreseen. Doctors groups and patient advocates said the bill must be abandoned.
Some Republicans worry a misfire on the Republican healthcare legislation could hobble Trump's presidency and set the stage for losses for the party in the 2018 congressional elections.
The Trump administration defended the healthcare plan, which they say will have a second and third phase that will entice consumers. Health and Human Services Secretary Tom Price said at the White House that Trump's plan would cover more individuals at a lower cost and it was "virtually impossible" to envision that 14 million people would lose insurance coverage by next year.
Democratic leaders in Congress said the bill could result in elderly people being kicked out of nursing homes as it simultaneously gives tax cuts for the richest Americans.
"How can they look their constituents in the eye when they say 24 million of you no longer have coverage and those of you who do have it, will have less coverage at more cost to you," House Democratic leader Nancy Pelosi said.
Trump himself made no comment on the report.
