Republicans are scrambling to shore up their Obamacare repeal legislation as congressional misgivings mount after a damning forecast on the bill’s impact.

Some 22 million Americans would lose health insurance over the next decade under the plan, said the non-partisan Congressional Budgetary Office (CBO).

Susan Collins of Maine is the latest Republican senator to come out against the proposal.

Republicans can afford to lose just two votes in their 52-seat Senate majority.

The Better Care Reconciliation Act would slash taxes on the wealthy, while cutting healthcare for the poor and nursing home residents.

Do Republicans have the votes?

Not currently. Senator Collins, Rand Paul of Kentucky and Ron Johnson of Wisconsin signalled on Monday that they would vote against even debating the bill.

Senator Collins, a moderate Republican, tweeted that the measure would “hurt most vulnerable Americans” in rural Maine, where “hospitals are already struggling”.

Nevada Senator Dean Heller, another moderate Republican, who faces re-election next year, said on Friday he would vote no.

Senate Republican leader Mitch McConnell, who wrote the bill, wanted it passed before the 4 July holiday, but that timetable is looking increasingly optimistic.

Two other conservative Republican senators – Ted Cruz and Mike Lee – said last week they were not ready to vote for the bill, but were open to negotiation.

With not a single Democrat supporting a bill they have derisively labelled “Trumpcare”, the margin of error is diminishing for Mr McConnell.

But the arm-twisting will continue – Vice-President Mike Pence is hosting several Republican senators for dinner on Tuesday.

It is worth remembering that political last rites were prematurely pronounced on the House of Representatives’ version of the Obamacare repeal plan after it was withdrawn on 24 March.

But six weeks later Republicans in the lower chamber reintroduced a slightly revised bill, which was narrowly passed.

How bad was the CBO report?

The 49-page CBO analysis said 15 million more people would be uninsured by next year alone under the Senate bill, largely because the unpopular Obamacare penalty for not having insurance would be eliminated.

Another seven million would lose coverage over the next decade, it predicted.

There were some positive points: the legislation would decrease federal deficits by $321bn over a decade, the budget office said.

It also found that average insurance premiums would be lower in 2020, but only because medical coverage would be much skimpier.

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The Senate bill makes it much easier for insurance companies to withhold minimum health benefits, such as maternity or mental healthcare, the budget office said.

Meanwhile, low-income and older people would be priced out of the market, the CBO predicted.

For example, a 64-year-old with an annual income of nearly $57,000 would pay a premium of about $20,500 a year in 2026, triple the amount expected under the Affordable Care Act (Obamacare).

President Trump pledged during the election campaign that he would not cut Medicaid, a health programme for low-income patients.

However, the Senate bill slashes more than $770bn from Medicaid, leaving 15 million fewer people covered, according to the CBO.

The budget office also notes the Senate plan scraps a key Obamacare regulation, paving the way for insurance companies to overcharge the government for certain plans.

The White House disputed the figures, saying: “The CBO has consistently proven it cannot accurately predict how healthcare legislation will impact insurance coverage.”