Republicans have already made the first steps towards repealing the controversial Affordable Care Act
A nonpartisan budget office in the US has estimated that a partial repeal of Obamacare would result in around 18 million Americans losing health insurance in one year alone.
The Congressional Budget Office's report examines the budgetary consequences of implementing HR 3762 - a Republican-led plan to partially repeal the Affordable Care Act (ACA).
The bill passed through the two houses of the US congress, but was vetoed by President Obama.
While the legislation failed, it has been seen as a potential blueprint for a replacement to President Obama's signature healthcare legislation.
According to the CBO report, the implementation of the bill without a replacement would have seen the number of uninsured Americans rise by 18 million in one year alone.
The report also suggests that a number of other longer-term repeal measures - such as the elimination of subsidies for insurance purchased through 'Obamacare' marketplaces - the number would increase to 32 million in 2026.
The report says: "Premiums in the nongroup market (for individual policies purchased through the marketplaces or directly from insurers) would increase by 20 percent to 25 percent [...] in the first new plan year following enactment.
"The increase would reach about 50 percent in the year following the elimination of the Medicaid expansion and the marketplace subsidies, and premiums would about double by 2026."
The CBO notes: "If the Congress considers legislation similar to HR 3762 in the coming weeks, the estimated effects could differ from those described here. In particular, the response of individuals, insurers, and states would depend critically on the particular specifications contained in such legislation."
The report comes amid Republican efforts to replace Obama's controversial healthcare legislation. A repeal of the ACA is all but inevitable as a result of Republican control of congress and Donald Trump's imminent move to the White House.
President-elect Trump has called the ACA a "catastrophe" which had to be replaced "very, very quickly". In a Washington Post interview over the weekend, he vowed "insurance for everybody" with any replacement legislation.
Republicans have taken the first steps towards repealing the act, although it remains unclear what it will be replaced with.
While the ACA has led to around 20 million Americans gaining health insurance, it has also faced severe opposition since its inception - including from Republicans, trade unions and small business groups.
It remains a divisive programme among voters, and concerns remain over its affordability.
Last weekend saw protests held against the planned repeal, with politicians such as Senator Bernie Sanders leading opposition to the Republican plans.