Senate Majority Leader Mitch McConnell (R-Ky.) at the Capitol on Wednesday. (Carolyn Kaster/AP)

Senate Republicans undertook the first steps in their plan to repeal the Affordable Care Act this week, launching a process they hope will yield a GOP health-care bill by week’s end.

Leaders won a key procedural victory Tuesday that allowed them to begin days of freewheeling debate. Senate leaders focused on passing a narrow set of changes to the ACA, known as “skinny repeal,” in hopes of continuing to debate a broader health-care plan in a House-Senate conference. But first, senators need to pass some sort of health-care measure in their chamber.

Over the next several days, the Senate could be in session nearly 24 hours a day — voting on amendments and bickering over the future of the nation’s health-care system while leaders work behind the scenes to finalize the details of the narrow bill.

The process will be unpredictable and chaotic, but Senate leaders believe it’s their best shot at passing a GOP-only health-care bill this year. We asked top Senate staffers to give us their best forecasts of what will happen over the next several days, and we’ve done our best to translate that into the questions and answers below.

Please note: Circumstances can change rapidly.

(U.S. Senate)

1. What are Senate Republicans trying to pass this week, and why is it so complicated?

Senate leaders are taking advantage of complex Senate budget rules, known as reconciliation, to pass a bill to revamp Obamacare without Democratic support. The measure will need only 51 votes instead of the typical 60 that is necessary for most legislation (there are 52 Republicans in the Senate, and Vice President Pence can break a tie).

The only hitch here is that budget bills come with a special set of rules requiring that every piece of the legislation must relate to the budget, spending, taxes and the deficit. The rules also allow for an nearly unlimited number of amendments from either party. That process, known as a “vote-a-rama,” means leaders can schedule votes all day and all night and they can do so with little or no warning.

The whole process began Tuesday when Senate Majority Leader Mitch McConnell (R-Ky.) promised GOP senators that the only way to keep the health-care debate alive was to vote to start debate on the House-passed bill to unwind Obamacare.

Senators approved the motion to start debate, 51 to 50, after Sens. Lisa Murkowski (R-Alaska) and Susan Collins (R-Maine) joined all 48 Democrats in voting against the bill, forcing Pence to break the tie.

Now that debate has started, McConnell’s goal is to keep Republicans focused on passing a “skinny repeal” that would gut the ACA’s individual and employer mandates and roll back at least one of the ACA taxes that Republicans revile. McConnell and his deputies are betting that it will be hard for GOP senators to oppose those basic concepts. If that passes, Republicans are expected to move on to negotiate a broader health-care plan with the House.

Republicans and Democrats can each spend 10 hours debating the bill before the vote-a-rama starts. It may not seem like a lot of time, but the countdown clock stops every time they vote and often when they take time out to debate an early amendment. That unpredictable schedule means the whole process could drag out for days.

2. Can the Senate leadership strategy work?

It seems possible. So far, no Republican senators have announced they oppose the idea of “skinny repeal.” Even Collins, who has been skeptical of every proposal leaders have made so far, told reporters that she wouldn’t rule out voting for the bill.

“Until I see what’s in it, I really can’t say,” Collins told reporters Wednesday. “I’m not ruling it out, because I don’t know what it would be.”

That said, Collins and several moderates who hail from states that expanded Medicaid under Obamacare remain skeptical of the plan. They worry that the most conservative GOP factions in the House would kill any chance of agreement by trying to force deeper cuts to programs for low-income people.

3. How many different health-care bills will senators vote on this week, and how long will the voting last?

That’s up to McConnell and his deputies. The Senate voted down one version of a plan to roll back and replace the ACA on Tuesday night with 57 senators — including nine Republicans — opposing the measure known as the Better Care Reconciliation Act (BCRA).

The Senate was expected to vote Wednesday on a plan to repeal large portions of the ACA, including the individual and employer mandates and most of the taxes included in the law. That version of the bill would also prevent patients from using federal tax subsidies to pay for health-insurance plans that cover abortion and institute a one-year ban on Medicaid payments to Planned Parenthood.

The abortion regulations and the repeal bill itself were both expected to fail. But there is nothing stopping leaders from tinkering with those bills and trying again.

The goal of these votes isn’t necessarily to pass the measures — in fact, top GOP aides say they expect nearly every one of the repeal-style measures to fail. Senators will have a chance to vote on a number of personally significant policies, such as the ban on abortion rights, in part to prove that the ideas don’t have the votes to become law. It also narrows the list of options for what could get consensus when a “skinny repeal” comes up later in the week.

4. What can Democrats do to stop the process?

Not much if Republicans decide to stick together. But they can cause headaches for the GOP by forcing votes on amendments that make Republicans cast public votes on a slew of difficult issues, such as protecting health care for disabled children and funding programs to combat opioid addiction.

Senate Minority Leader Charles E. Schumer (D-N.Y.) has not yet revealed his full strategy, but Democrats are already lining up hundreds of amendments for the vote-a-rama. Democrats are confident that some of their amendments, including a measure that would end debate and send legislation to committees for further debate, could pass and make it harder for any eventual bill to pass.

Complicating matters further is the possibility that McConnell could end the vote-a-rama with an amendment to wipe out any amendments that have been approved, forcing the Senate to revote on a stripped-down bill.

5. Which Republicans are still undecided, and what do they want?

While most rank-and-file Republicans say they support McConnell’s plan to pass a narrow bill and keep the conversation alive, the plan risks angering senators on the GOP’s ideological extremes.

Conservatives such as Sens. Ted Cruz (R-Tex.) and Mike Lee (R-Utah) have said they want full repeal. Moderates and those from states that expanded Medicaid, such as Collins, Murkowski, Rob Portman (R-Ohio) and Shelley Moore Capito (R-W.Va.), don’t want to risk cuts to Medicaid.

The plan would be dead if three of those holdouts voted against the final bill.