The House Republican health care bill would leave 23 million fewer Americans with health insurance by 2026 than under Obamacare, the nonpartisan Congressional Budget Office said Wednesday.

The highly anticipated CBO score is likely to trigger another round of negative headlines and more hurdles for Republicans as they look to advance a controversial piece of legislation that was passed in the House earlier this month.

The CBO also found the bill would reduce deficits by $119 billion compared with Obamacare.

Eager to notch a political win in the GOP's years-long mission to repeal Obamacare, Republican lawmakers took a gamble by voting before the CBO could analyze last-minute changes to the bill.

Related: Senate Republicans already didn't like the House bill ...

The new CBO report will serve as an important report card for Senate Republicans as they deliberate over their own version of the health care bill.

The report also shed some light into how the House GOP bill, titled the American Health Care Act, would change the nation's individual health insurance market.

The legislation would end enhanced funding for Medicaid expansion, while overhauling the entire Medicaid program. It would eliminate the mandates that require nearly all Americans to have coverage and companies with more than 50 workers to provide health benefits. And it would jettison Obamacare's taxes on the wealthy, insurers and others, while allowing insurers to charge more to older policyholders.

The agency has already issued two reports on earlier versions of the GOP health care bill, but lawmakers continued to make changes up until the last minute to secure enough votes for passage.

The legislation that ultimately passed would allow states to waive two key Obamacare protections for those with pre-existing conditions. Insurers in these states would be allowed to charge higher premiums to those with pre-existing conditions if they let their coverage lapse. Carriers would also be allowed to offer skimpier plans that would have lower premiums, but not cover as many benefits. But lawmakers also allocated additional money to a stability fund to help states cover high-cost enrollees.

Related: What CBO got right - and wrong - on Obamacare

These last-minute amendments would divide the market into three, with each having very different outcomes in terms of coverage and premiums, the CBO found.

About one-sixth of the population live in states that would opt to make major changes to their insurance regulation, lowering premiums for the young and healthy, but likely leaving many of the sick unable to afford coverage because their rates would continue to escalate.

One-third of Americans live in states that would make "moderate changes" to regulations. Their average premiums would be lower by 2026 than they would be under Obamacare, but mainly because they would have fewer benefits. Younger people would see "substantially larger" reductions in premiums, while older enrollees would have "substantially smaller" ones.

The remaining half of the country would live in areas that would retain Obamacare's protections. They would see minimal decreases in premiums, though the amount would vary widely by age.

Here are the top takeaways on what the CBO found.

1. 23 million fewer will be insured

The recent revisions to the House GOP bill would slightly lessen the harsh impact of the Republican plan to repeal Obamacare. CBO's assessment of the original legislation found that 24 million fewer people would have coverage by 2026.

Under the latest bill, some 51 million non-elderly Americans would be uninsured by 2026, compared to 28 million projected under Obamacare. This would reverse major gains in coverage among the uninsured since Obamacare's exchanges opened and Medicaid expansion went into effect in 2014.

The legislation would still hit poor Americans the hardest. Some 14 million fewer people would qualify for Medicaid in 2026, the same number as in CBO's original assessment.

The projected decline in coverage is one of the main objections critics have to the GOP proposal. CBO's score of the initial bill unleashed a flood of criticism from Democrats, Obamacare supporters and lawmakers' constituents.

Lawmakers have had to contend with supporting a bill that would strip away coverage from so many Americans. They've been particularly divided over making drastic cuts to Medicaid.

Complicating matters further: President Trump's past promises on coverage. He vowed early this year that the Republican bill will provide "insurance for everybody."

Related: Trump promises his Obamacare replacement plan will cover everybody

2. Average premiums would be lower ... for the young and healthy

The impact on premiums would depend greatly on where one lives.

In the states that don't request waivers, average premiums would be about 4% lower than under Obamacare, mostly because younger and healthier consumers would be the ones purchasing policies. That's because the GOP legislation would allow insurers to charge people in their 50's and early 60's higher premiums compared to younger enrollees. This provision has raised the ire of the influential AARP and sparked concerns among many lawmakers.

In areas that opt to make moderate changes to Obamacare's regulations, premiums would be reduced by 20%, on average, but mainly because insurers would cover fewer benefits. Rates, however, would vary widely depending on what benefits states require insurers to cover. Again, younger enrollees would see much larger premiums reductions.

And in the places that opt to jettison the law's protections, premiums would vary widely based on a consumer's health status and the benefits provided in the policy. Less healthy people would face "extremely high premiums," even with the funding lawmakers would give to states to help reduce their rates. The CBO did not calculate an average change in premiums.

Just how much consumers pay for premiums also depends greatly on their income. Both Obamacare and the GOP bill provide refundable tax credits to help people cover the cost of coverage, but Obamacare's credits are much more generous for lower-income consumers.

The CBO found that those with incomes of $26,500 would pay less for policies at all ages under Obamacare in 2026 than under the GOP bill in states that do not waive Obamacare's regulations or make moderate changes. There's one exception: A 21-year-old would pay $1,250 on average in states that make moderate changes, compared to $1,700 under Obamacare. That policyholder would pay $1,750 in states that did not waive the regulations.

But someone earning $68,200 would fare better under the GOP bill in nearly all circumstances, though younger consumers would see much greater reductions than older ones.

Related: High-risk pools won't match Obamacare's protections for pre-existing conditions

In a statement, House Speaker Paul Ryan was defiant that the CBO confirms the GOP's "mission" of lowering premiums and the deficit.

"We are on a rescue mission to bring down the cost of coverage and make sure families have access to affordable care," Ryan said. "This CBO report again confirms that the American Health Care Act achieves our mission: lowering premiums and lowering the deficit. It is another positive step toward keeping our promise to repeal and replace Obamacare."

3. Many people would pay more for essential health benefits

Lower average premiums, however, don't mean that Americans' health care costs would go down. Many people would pay more for what are considered essential health benefits under Obamacare.

Obamacare requires insurers to cover 10 key services, including maternity, mental health, substance abuse and prescription drugs. The law would allow states to waive that federal mandate and replace it with their own set of required benefits. In states that opt for the waiver, consumers would see "substantial increases in out-of-pocket spending on health care or would choose to forgo the services," according to the report.

In particular, spending on maternity care, mental health and substance abuse could increase by "thousands of dollars" for those who need those benefits, CBO found. Also, states would likely no longer require insurers to cover rehab and pediatric dental care.

Consumers in these states would also lose key Obamacare financial protections. The health reform law capped enrollees' annual out-of-pocket spending and prevented insurers from placing financial limits on coverage. However, these only apply to essential health benefits, so there would be no ceiling on services that aren't included in states that waive the provision.

4. The bill would save less than previous bill

The legislation would reduce federal deficits by $119 billion over 10 years, the CBO found.

An earlier version of the bill would have lowered the deficits by $150 billion, but lawmakers then added more money to a stability fund for states to deal with costly enrollees.

The savings figure should allow a small sigh of relief for Republicans. Under budget reconciliation -- a process that allows the Senate to pass a bill with only 51 simple majority "yes" votes -- the GOP bill must hit a $2 billion savings goal over the next decade.

Related: Would the House really need to vote again on health care?

If that threshold had not been met, the House would have had to vote again on a new bill.