A preliminary attempt to estimate the impact of Senate Republicans' "skinny repeal" bill — their last-ditch attempt to repeal at least parts of Obamacare — suggests that it would result in 16 million fewer Americans having health insurance, according to a copy of a Congressional Budget Office report Senate Democrats shared with Vox on Wednesday night.

So far, Senate Republicans have not produced a skinny repeal bill for the CBO to evaluate.

However, the kinds of policies that might be included in such a bill have been reported in the press — and have been previously evaluated by the CBO. Senate Democrats asked the CBO to package together previous reports on the policies expected in skinny repeal to get a sense of the impact these policies could potentially have.

That analysis found that the rumored provisions of skinny repeal would result in roughly 20 percent premium hikes, in addition to millions fewer Americans having health insurance compared with under Obamacare.

“We just heard from the nonpartisan Congressional Budget Office that under such a plan, as reported in the press, 16 million Americans would lose their health insurance and millions more would pay a 20 percent increase in their premiums,” Sen. Chuck Schumer (D-NY) said on the Senate floor.

The skinny repeal idea, which emerged just before Republicans voted to begin debate on Obamacare repeal, would roll back the individual mandate and curb some of the Affordable Care Act’s taxes, but leave much of the rest of the law in place. Skinny repeal is believed to be the only option that enough Republicans will vote to pass and that could still be called Obamacare repeal.

The provisions Senate Democrats asked the CBO to evaluate in this analysis include the following, according to a senior Democratic aide:

Repealing the individual mandate

Repeal the employer mandate

Repealing the medical device tax

Defunding Planned Parenthood

Repealing the Prevention and Public Health Fund

Repealing the Community Health Center Fund

A Senate Democratic aide provided the following chart to Vox, which shows how many millions of people would be uninsured under current law compared with how many would be uninsured under a version of the Better Care Reconciliation Act modified to include the rumored components of “skinny repeal.”

Vox’s Dylan Scott has explained why Republicans’ skinny repeal plan, if passed, would have serious repercussions for the number of uninsured Americans.

“That policy could prove extremely disruptive to the individual insurance markets, where people buy coverage if they don’t get it through their employers or the government, if it became law,” Scott explains. He continues:

“Health insurance works as a business only if as many healthy people buy insurance as possible to offset the costs of paying for sick people’s health care. Getting rid of the Obamacare requirement that people buy health insurance or face a penalty could lead healthy people to avoid insurance altogether.”