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

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

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

At least six Republican senators have said they’re not ready to support the current version of the health-care bill, and McConnell can 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 for moderates, as well as more regulatory relief upfront for conservatives, who particularly want to allow states to charge people with pre-existing conditions higher premiums.

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

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

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

The Trump administration quickly blasted the CBO report, saying the 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 22M uninsured

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

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

Senate Minority Leader Chuck Schumer said the CBO report makes it clear "this bill is every bit as mean as the House bill.” He added, “I don’t count Senator McConnell out, but this is such a bad bill that even his legislative wizardry is having a rough time here.”

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

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

The CBO estimated the Senate health bill would raise costs for many people currently enrolled in private insurance and slash Medicaid 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 savings from the version passed by the House in May.

Higher costs

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

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

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

Related: Cornyn expects to move ahead on Senate health bill Wednesday

In 2026, average premiums would be about 20 percent lower than they would be under Obamacare. That’s in part because coverage would be skimpier, and people would face higher deductibles and other 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-level plan covering 70 percent of their expected health costs under existing law. That person would face a $20,500 premium for the same coverage under the Senate bill and get no subsidy.

Market effects

The CBO estimated that the individual health insurance markets would be stable in most parts of the country under both the Senate GOP 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 decide to purchase insurance — and markets with few purchasers are less profitable for insurers,” CBO said.

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

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

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