(CNN) After weeks of cloak-and-dagger discussions, the Senate Republican health care bill could come up for a vote as early as Thursday.

The new legislation would not upend Obamacare as abruptly as the the bill the House passed in May, but both call for significant cuts. On Monday, nonpartisan Congressional Budget Office estimated that if the Senate bill becomes law, 22 million more Americans would be uninsured by 2026 than if Obamacare remained in place.

Here is a breakdown of how the Senate legislation stacks up to the House version -- the American Health Care Act -- and how both compare to Obamacare.

Note: This will be updated as we make our way through the text of the bill and CBO report.

The CBO said in its hotly anticipated report Monday that passage of the Senate bill would likely increase the ranks of the uninsured by 22 million over the next 10 years . The House bill would do about the same, with an estimated 23 million fewer Americans covered than under Obamacare.

Obamacare greatly expanded Medicaid and mostly paid for it, allowing states that accepted the funding to provide coverage to millions of low-income Americans who couldn't afford it before.

The Senate bill would continue Medicaid expansion under Obamacare for three years, then begin to roll it back in 2021.

The overall program would also change. States would eventually receive a fixed amount -- unlike the current open-ended funding requirement -- in the form of a block grant or a figure based on the number of enrollees. In the Senate bill, that dollar amount would grow more slowly because, beginning in 2025, it would become tied to inflation, a less generous index than medical costs.

Obamacare guarantees coverage even for people with pre-existing conditions and bans insurers from charging people based on their health. The House bill would allow states to opt out of the latter provision. The Senate bill does not, but -- as explained below -- insurers could provide skimpier coverage in states that get waivers for essential health benefits.

Obamacare required every health plan to cover certain essential benefits -- everything from maternity and hospital care to prescription drugs and mental health. Both the Senate and House bill would allow states to redefine what qualifies as an "essential" element of a health care plan. Before Obamacare, insurers could sell coverage that didn't cover things like mental health or prescription drugs. By stripping out these benefits, insurance premiums would in certain cases becomes cheaper. But policies would also cover fewer services.

Obamacare, in accordance with federal law, provides funding and reimbursements to the women's health care provider, with the exception that none of that money can directly pay for or offset abortion services. Both the House and Senate bill would immediately cut off Planned Parenthood for at least one year.

Obamacare helped raise money for its expansion of health coverage by levying two new taxes on the wealthy. Both the House and Senate bills eliminate Obamacare taxes on the wealthy and insurers.

Because it forced people to obtain health insurance or pay a penalty, Obamacare provided tax subsidies to help people -- up to a certain income level -- pay for it. The Senate bill is largely in line with Obamacare, tying subsidies for people paying for individual coverage to prices where they live and their incomes. The House legislation would only consider age.

Under Obamacare, nearly everyone either had to obtain health insurance or pay a penalty. That requirement would be fully reversed by the Senate bill. The House version also removed the mandate, but includes a provision that allows insurers to impose a 30% surcharge on individuals who allow their coverage to lapse, then want to sign on again. The effect is to use the threat of that one-time charge to encourage people to stay on their plans. The Senate bill gets rid of that surcharge.

Obamacare helped young people get insured by allowing them to stay on their parents' insurance until they are 26. Neither the House nor Senate bill would remove that provision.

Most Americans actually get their health insurance through an employer and not through the government or health insurance exchanges. Both the House and Senate bill would strip the Obamacare provision requiring larger employers to provide affordable coverage.