April 30, 2017 1035 GMT
By 2026 that number would shoot up to 24 million, the Congressional Budget Office said, largely because the bill would undo the Obamacare rule mandating people to have health insurance, AFP wrote on Tuesday.
It also said that the measure currently before Congress – backed by Trump and House Speaker Paul Ryan – would reduce the federal deficit by $337 billion over the next decade.
Part of that reduction comes from the plan's phase-out of the Medicaid expansion by 2020, which would save a massive $880 billion.
Average health coverage premiums would rise 15 to 20 percent in 2018 and 2019 for individual policy holders, it said.
The projection was seen as a black eye on Trump's repeal-and-replace plan, which already faced substantial opposition from within his own party over fears it would leave millions uninsured.
However the online magazine Politico, citing a White House document, reported that the executive's own analysis forecast that 26 million people would lose coverage over the next decade, higher than the 24 million estimated by the CBO.
Trump and his inner circle nevertheless insist that the plan is a vast improvement over Barack Obama's signature health care reform – which many Republicans say caused insurance costs to spike.
"We disagree strenuously with the report that was put out," said Health and Human Services Secretary Tom Price.
Some conservative Republicans have argued that the proposal is too similar to Obamacare, while party moderates warn that it provides insufficient funding to help millions retain or purchase coverage.
Trump campaigned for a full year on repealing and replacing Obamacare, repeatedly stating his desire for health care coverage for "everybody."
But some Republican lawmakers were clearly worried.
"It's awful," Senator Bill Cassidy said of the CBO projection, according to the Washington Examiner.
Facing mounting concern about the plan, Trump met Monday with "victims of Obamacare" to highlight the Republican replacement.
The GOP plan rolls back the expansion of the Medicaid health care program for the poor by 2020, replaces government subsidies with tax credits to help individuals buy insurance and scraps Obamacare taxes.
It preserves two popular Obamacare provisions: insurance companies cannot refuse coverage due to pre-existing conditions, and dependents can remain on their parents' insurance plan until age 26.
Obamacare – formally known as the Affordable Care Act – helped 20 million Americans gain coverage.
Under the Republican plan, premiums would begin decreasing by 2020, CBO said, due to grants that could bump up tax credits to poor or working-class Americans, and because younger people would be projected to sign up for coverage.
But costs by 2026 would be some 20 to 25 percent higher for people age 55 to 64, CBO said. For the elderly poor it would be disproportionally difficult.