Story highlights The report was prepared at the request of Democratic congressional leaders

The report used the 2015 Republican legislation that would have repealed Obamacare's coverage

(CNN) Repealing major Obamacare provisions without a replacement plan in place would quickly strip 18 million Americans of their insurance and cause premiums to skyrocket, according to a new Congressional Budget Office report released Tuesday.

The number of uninsured people could climb to 32 million by 2026, the report from the nonpartisan office said. Premiums, which would rise by up to 25% initially, would double by 2026.

Though the bill the CBO studied is no longer in play, the findings lay out the daunting challenge Republicans and President-elect Donald Trump have ahead as they seek to fulfill their promise to swiftly repeal the Affordable Care Act. A growing chorus of lawmakers and health care industry experts have demanded to see leaders' replacement plans before Congress votes to repeal major parts of the law.

The report, prepared at the request of Democratic congressional leaders, looked at the 2015 Republican legislation that repealed Obamacare's coverage mandates, taxes, subsidies and Medicaid expansion, but did not include replacement plan. That bill was vetoed by President Barack Obama.

Democrats quickly jumped on the report, saying the GOP plan will hurt Americans and raise health care costs.

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