At least three Republican senators said they would vote to blockthe current version of their party’s health-care bill fromadvancing, endangering Majority Leader Mitch McConnell’s plan torepeal Obamacare.

Related: Four GOP senators spurn health plan aimed atunifying party

Republican Susan Collins of Maine late Monday said she wouldvote against a key procedural step, joining Rand Paul of Kentuckyand Dean Heller of Nevada.

A new estimate from the Congressional Budget Office, which foundthe bill would leave an additional 22 million Americans withouthealth insurance in a decade, has moved McConnell further awayfrom the 50 votes he needs to pass the measure.

"It’s a terrible bill," Paul said. Collins, a moderate, said theCBO analysis showed the bill “doesn’t fix” Obamacare’sproblems.

Republican leaders insisted they still hope to hold a final votethis week, and McConnell did get one piece of good news in the CBOestimate: an extra $200 billion in deficit savings compared to theHouse-passed bill.

Some or all of that funding could be used to boost programs orsubsidies to help win over moderates like Rob Portman of Ohio,Shelley Moore Capito of West Virginia, Lisa Murkowski of Alaska andCollins, who have been seeking more help for opioid addiction,rural areas, subsidies for older people or slimmer Medicaidcuts.

At least six Republican senators have said they’re not ready tosupport the current version of the health-care bill, and McConnellcan only afford to lose two and still pass the bill.

Regulations and funding

If a deal is to be had, it would require more money formoderates, as well as more regulatory relief upfront forconservatives, who particularly want to allow states to chargepeople with pre-existing conditions higher premiums.

“The current draft doesn’t have the votes to pass,“ Ted Cruz ofTexas said, “but I believe we can get to yes.”

Related: Poll: What do you think about the GOP Senate draftof the AHCA?

Senator Ron Johnson of Wisconsin warned GOP leaders that holdinga vote this week “would be a mistake. If Leader McConnell saysfailure is not an option, don’t set yourself up for failure." Headded that he didn’t think he would get enough information on thebill to be able to support advancing the bill this week, althoughhe allowed that “lightning” could strike.

The Trump administration quickly blasted the CBO report, sayingthe agency has a “history of inaccuracy.”

‘Didn’t help’

But senators were taking the CBO estimate more seriously.

Related: Senate GOP health proposal would leave 22Muninsured

“If you’re looking at this as a political vote, the CBO reportdidn’t help you,” said Lindsey Graham of South Carolina, who saidhe won’t block the measure. “So I think it’s going to be harder toget to 50, not easier.”

Cruz blasted in particular the near-term cost increasesthat the CBO estimated. "At this point, we need to do significantlymore to lower premiums," he said.

Senate Minority Leader Chuck Schumer said the CBO report makesit clear "this bill is every bit as mean as the House bill.” Headded, “I don’t count Senator McConnell out, but this is such a badbill that even his legislative wizardry is having a rough timehere.”

When asked about the CBO score, House Speaker Paul Ryan said themillions more people who would be uninsured under the Republicanplan would have the choice to not “buy Obamacare” once theindividual and employer mandates are repealed.

“It’s not that people are getting pushed off a plan, it’s thatpeople will choose not to buy a plan they don’t like or want,” Ryansaid in an interview that aired on Fox News on Tuesday.

The CBO estimated the Senate health bill would raise costs formany people currently enrolled in private insurance and slashMedicaid by billions of dollars. It would reduce the deficit by$321 billion over a decade, according to the nonpartisan agency,significantly higher than the $119 billion in estimated savingsfrom the version passed by the House in May.

Higher costs

Complicating the efforts of GOP leaders to win over holdouts isthe CBO’s estimates that many Americans will face out-of-pocketcosts and insurance premiums far higher than they are now.

The biggest increase in the uninsured would come from the bill’srollback of Medicaid, the state-federal program that covers thepoor. The GOP bill cuts spending on Medicaid by $772 billion over adecade, which would result in 15 million fewer people enrolled inthe program in 2026 than under current law. Another 7 millionwouldn’t have coverage in the individual insurance market.

The CBO estimated that the law would lower premiums in the longterm, but raise out-of-pocket costs. Premiums would rise over thenext several years and then fall, relative to current law.

Related: Cornyn expects to move ahead on Senate health billWednesday

In 2026, average premiums would be about 20 percent lower thanthey would be under Obamacare. That’s in part because coveragewould be skimpier, and people would face higher deductibles andother cost-sharing.

For example, a 64-year-old making $56,800 in 2026 would have a$6,800 annual premium after an $8,500 subsidy for a silver-levelplan covering 70 percent of their expected health costs underexisting law. That person would face a $20,500 premium for the samecoverage under the Senate bill and get no subsidy.

Market effects

The CBO estimated that the individual health insurance marketswould be stable in most parts of the country under both the SenateGOP plan and under Obamacare. Under the Republican plan, though,insurers might withdraw from some rural parts of the country,because they’d have too few customers to operate profitably.

“The reductions in subsidies would lead fewer people to decideto purchase insurance — and markets with few purchasers are lessprofitable for insurers,” CBO said.

The political prospects for the overall bill remain unclear.Republican leaders are hoping to hold an important procedural voteon Tuesday or Wednesday to set up a vote on final passage at theend of the week.

While Heller and Collins have cited the cuts to Medicaid fortheir opposition, a bloc of four conservatives -- Paul, Cruz,Johnson and Mike Lee of Utah -- oppose the proposal for differentreasons: They said the bill doesn’t go far enough in undoingObamacare.

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