The Republican healthcare bill has cleared two key congressional committees, despite concerns that the plan’s impact on the budget is unclear.

The House of Representatives Ways and Means backed the bill, followed by the Energy and Commerce Committee, moving it to a full chamber vote.

Republicans, who control both chambers of Congress, hope to pass their replacement for Obamacare by mid-April.

But it faces resistance from Democrats, hospitals and even some Republicans.

The Energy and Commerce Committee approved the bill along party lines after more than 24 hours of debate over the proposed legislation.

“This is an historic step, an important step in the repeal of Obamacare,” said Republican Representative Kevin Brady, chairman of the House Ways and Means Committee.

It approved the bill, which was unveiled on Monday, after nearly 18 hours of debate.

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The committee made no changes to the draft legislation – known as the American Health Care Act – despite Democratic attempts to introduce amendments.

The new plan would dismantle much of Mr Obama’s 2010 Affordable Care Act.

It also:

• limits future federal funding for Medicaid, which covers low-income people
• abolishes the requirement that everyone should be insured
• replaces subsidies with tax credits

But the American Hospital Association (AHA), which represents about 5,000 hospitals and health networks, said current provisions for “our most vulnerable” would be thrown into doubt under the plan.

The president of the AHA said in a letter to Congress the ability to assess the bill was “severely hampered” by the lack of a proper cost estimate.

The Congressional Budget Office is not expected until next week to put a price tag on the proposed overhaul of the more than $3tn (£2.4tn) US healthcare system.

Democrats continue to argue that it is impossible to push through a bill without knowing its cost and how many Americans would be affected.

Senator Tom Cotton, a conservative Republican from Arkansas, shared that concern in a series of tweets on Thursday after the vote.

He told House members to “pause, start over” and “get it right, don’t get it fast”.

“What matters in the long run is better, more affordable [healthcare] for Americans, NOT House leaders’ arbitrary legislative calendar,” he added.

Some moderate Republicans are also concerned people will be stripped of cover by the legislation.

President Donald Trump is meanwhile exercising his vaunted salesman skills to rally support behind the health bill.

On Thursday, he tweeted that “healthcare is coming along great” and “it will end in a beautiful picture!”

House Representative Tom Cole, who joined lawmakers at a meeting with the president on Wednesday, told Bloomberg Mr Trump had suggested weekly meetings.

Some lawmakers have been invited to hang out on Thursday at the White House’s bowling alley, according to the report.

Mr Trump has dined with former foes including Senator Lindsey Graham and Senator Ted Cruz, who brought his family to the White House on Wednesday night.

Overall, the plan is expected to cover fewer people than those who gained insurance under the Obama administration’s Affordable Care Act.