Your guide to the next steps in the Senate health care debate

The Obamacare repeal debate has begun in the Senate. That's about all we know for sure.

A slim vote, 51 to 50 with two Republican senators dissenting, to open debate was a huge victory for Republicans' hopes of passing some kind of health care bill, and puts health insurance for millions of Americans at risk.

But Republicans haven't actually settled on what legislation they are trying to pass. Bills to cleanly repeal much of Obamacare or to more fully repeal and replace it don't currently have the votes. In just the past few days, the idea of a much smaller bill, repealing just a few of Obamacare's most unpopular provisions, surfaced.

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That final destination must be sorted out in a mad rush over the next few days, with the Senate's arcane budget rules and a vote-a-rama that will open up Republicans to a flood of Democratic amendments designed to force tough votes promising to make the process even more treacherous.

Senate Republicans scored a victory Tuesday. But the ultimate result is far from clear. Let's break down how the next few days will look.

This is what will actually happen in the Senate over the next day or so

The Senate's process from here is byzantine. The vote on Tuesday was technically to start debate on the House's health care bill, but nobody expects that to be the actual legislation the Senate ultimately votes on.

This is what we expect to happen now, per Senate aides. Remember: Things are fluid. Timing and order could change.

• Two hours of debate on the clean (partial) Obamacare repeal bill, known as the Obamacare Repeal Reconciliation Act. Time is divided evenly between Democrats and Republicans.
• Two hours of debate on the repeal-and-replace plan that Republicans have been drafting since May, the Better Care Reconciliation Act. Time is divided again evenly between Democrats and Republicans. (During debate, each party can decide to give up some of its time if it wants.)
• Vote on the repeal-and-replace bill. Because of some last-minute changes to the legislation, it is expected to require 60 votes. So at some point before the vote, Democrats would likely raise a "point of order," arguing that the Better Care Reconciliation Act runs afoul of the Byrd Rule, which allows some Senate bills dealing with the federal budget to pass without a filibuster. The Senate parliamentarian would have to rule whether their objection is correct. (The parliamentarian, Elizabeth MacDonough, has already found that parts of the current version of the repeal and replace bill violate the Byrd Rule.) Traditionally, senators go along with the parliamentarian's recommendation. Assuming that happens, the Better Care Reconciliation Act would need Democratic support to pass — so it would likely fail, ending Republicans' hopes of repealing and replacing Obamacare at the same time.
• Vote on the clean partial repeal bill, the ORRA. The partial repeal bill would need 51 votes, but it is expected to fail as well because too many Republicans oppose repealing without a replacement.
• 20 hours of debate on the Senate floor. That's 20 hours on the Senate floor, not 20 hours in the rest of the world, so those 20 hours could take a couple of days if senators pause for breaks. Democrats and Republicans will take turns making speeches about health care. Democrats can use certain tactics — like asking for a full bill to be read out loud — to make the process more painful.
• Vote-a-rama. There will then be what's called vote-a-rama — quick up-or-down votes on whatever amendments Republicans and Democrats offer on the bill. Amendments must be considered relevant to health care, and they need 51 votes to be approved. They would technically be amendments to the House bill, if the previous two Senate bills have already failed or not been voted on yet. Democrats plan to use this time to force Republicans to take votes on politically unpopular measures, even if those amendments have little chance of making it into the final bill.
• Final bill. McConnell will eventually offer a final substitute, encompassing the actual plan that Senate Republicans want to pass. This could be the so-called "skinny repeal" billthat surfaced Tuesday morning.
• Vote on passage. That needs 51 votes to pass. Vice President Mike Pence can break a 50-50 tie.

In the meantime, Senate Republican leaders must figure out what bill they actually want to pass in the end. At the start of debate, they either didn't know or hadn't said.

There are three competing proposals at the moment:

1. "Skinny repeal," the new proposal, which would get rid of the individual mandate along with a few other unpopular provisions
2. A full repeal of Obamacare's spending and health insurance coverage expansion with no replacement (the Obamacare Repeal Reconciliation Act, or ORRA for short)
3. A repeal-and-replace plan that senators have been working on for months (the Better Care Reconciliation Act, or BCRA)

The ORRA is almost certainly dead; enough Republicans have said that they won't support repealing Obamacare without a replacement in hand. But McConnell is nonetheless bringing it up for a vote, to give conservatives a chance to vote on the clean repeal bill they have been asking for.

The BCRA also appears doomed. The moderate and conservative wings of the GOP conference were pulling the bill in opposite directions; the former wanted fewer Medicaid cuts, while the latter wanted more of Obamacare's insurance regulations to be rolled back.

McConnell is nonetheless planning to bring up the BCRA for a vote. But because of last-minute changes to the bill and the Senate's rules governing "budget reconciliation," it is expected to need 60 votes to pass.

That would require Democrats to support the bill, which almost certainly won't happen. But it nonetheless gives Senate Republicans a vote on the repeal-and-replace legislation they've been working on for months.

That leaves the so-called "skinny repeal" bill. As they struggle to whip up a majority, Senate leaders have started promising reluctant senators that if they pass a bill, any bill, they will go into negotiations with the House and fix the legislation there.

In order to get to conference, though, leadership needs a bill that can get 50 votes. Eliminating the penalty for Obamacare's individual mandate — possibly along with its employer mandate and some of its taxes on the health care industry — might be the only plan that can win such broad support within the Republican conference.

Three health care lobbyists told Vox that this was the path forward being charted by Senate leadership. One lobbyist said the bill could be narrowed to the "lowest common denominator product."

Therefore, "skinny repeal" is our best guess for the actual bill that McConnell will put up for a vote for final passage. But a lot could change in the next day or two.

As Vox's Jeff Stein documented, Democrats can't stop this debate from moving forward. But they can try to make it more painful for Republicans. Right away, when McConnell announced he would offer the clean repeal bill as his first amendment, Sen. Patty Murray (D-WA) objected, forcing the clerk of the Senate to read the entire bill on the Senate floor.

The vote-a-rama gives Democrats many opportunities to force votes on amendments explicitly designed to be tough for Republicans. None of them are likely to pass, but Democrats will still bring them up.

Here's an early and partial list of amendments currently under consideration, as revealed in conversations with several Democratic aides:

• A proposal that would eliminate any tax cuts in the bill that would go to the richest 2 percent of Americans
• A proposal to ensure that the bill does nothing to reduce the budget of Medicaid
• A proposal to prevent any funding cuts in the Republican health bill from hitting rural hospitals
• A proposal to prevent any funding cuts from deepening the opioid crisis
• A proposal to advance reinsurance, which would give states federal money to give insurers funding for their most expensive, high-cost enrollees
• A proposal to say that nobody with cancer or diabetes can be harmed by the Republican bill