The big difference: a Sept. 30 deadline to use a rule that allows Senate Republicans to pass a measure with just 50 votes.

Like earlier, failed plans, the Graham-Cassidy measure would allow states to dismantle rules that prevent older, sicker people from being charged higher insurance premiums.

It would cap the federal outlay for traditional Medicaid, which could jeopardize coverage for the most vulnerable. And it would almost certainly lead to millions more Americans lacking insurance, health care policy experts say.

“It has all of the worst elements of the House bill that was passed in May and the Senate bill that was defeated in August,” said John Baackes, CEO of L.A. Care Health Plan.

But none of that may matter to Republican senators facing extreme pressure to finally pass something — anything — that scraps the health law and fulfills seven years of campaign promises.

Next week’s expiration of the rule allowing Republicans to pass a bill without any Democratic support has “concentrated Republican minds,” said Dean Clancy, a conservative health policy analyst who supports the plan. “This is their last chance to show they can govern on health care, and if they can’t govern on health care, what can they govern on?”

“They all hate health care,” said a GOP lobbyist on background. “They don’t know where to go on it. They just want to take a vote and be done with it.”

Yet with little more than a week until the witching hour, the effort is still uphill. Susan Collins (R-Maine) and Rand Paul (R-Ky.) are widely expected to vote against the bill, meaning Republicans can’t afford to lose a single additional vote. Even if the measure clears the Senate, the House would then need to pass the package without making any changes to it — a highly uncertain prospect.

But the fact that the bill remains alive — with Senate leaders and the White House scrambling to secure 50 votes for a vote next week — speaks to how desperate Republicans are to scrap Obamacare and notch a legislative victory.

“The substance really doesn’t matter,” said Kathy Hempstead, who oversees coverage programs for the Robert Wood Johnson Foundation, likening it to frenzied efforts to kill a zombie in the movies. But she added: “We’re not talking about killing a zombie. We’re talking about how we finance health care for 100 million people.”

Republicans might fear the political consequences of not taking action — including potential primary challenges in 2018 — more than the fallout from passing a bill that could lead to problems for their constituents further down the road.

Most are acutely aware that Obamacare repeal remains a galvanizing issue for the GOP base. More than half of Republicans surveyed in the latest POLITICO-Harvard T.H. Chan School of Public Health poll said scrapping Obamacare should be a top priority for Congress — a higher percentage than for any other issue surveyed.

Chuck Grassley (R-Iowa), chairman of the Judiciary Committee, crystallized the conflict in unusually candid comments on Wednesday.

“You know, I could maybe give you 10 reasons why this bill shouldn’t be considered,” Grassley told reporters. “But Republicans campaigned on this so often that you have a responsibility to carry out what you said in the campaign. That’s pretty much as much of a reason as the substance of the bill.”

Which explains why many of the concerns that torpedoed earlier bills may be getting overlooked now.

Most notably, health care policy experts argue the plan doesn’t do enough to protect individuals with pre-existing conditions, a linchpin promise of President Donald Trump and other Republicans. That’s because it would allow states to seek waivers from Obamacare’s rules to permit insurers to hike premiums for individuals with costly medical conditions, potentially making coverage prohibitively expensive.

“The bill’s broad language opens the door to theoretically unlimited premium upcharges based on any factor other than gender, race, religion, or national origin,” reads an analysis by policy experts at Georgetown University’s Center on Health Insurance Reforms. “This includes surcharges upon renewal of an existing policy — so if you’re healthy at enrollment but get sick mid-year, you may get a premium hike for your trouble.”

The Senate’s repeal package would also make big cuts to Medicaid by scrapping Obamacare’s expansion of the program and overhauling the funding formula so that it’s no longer an open-ended entitlement program.

States would receive block grants instead, which Republicans argue would allow them to deliver coverage in cheaper, innovative ways, unshackled from burdensome federal rules. But roughly two-thirds of states would end up with less funding to deliver coverage — a total of $160 billion in cuts over a decade, according to the nonpartisan Kaiser Family Foundation.

“Flexibility doesn’t matter if you don’t have the resources to carry out an innovative program,” said Daniel Hilferty, CEO of Independence Blue Cross, which does business in Pennsylvania and New Jersey.

Thirty-one states that expanded Medicaid under Obamacare would see average funding reductions of 11 percent, while those that didn’t implement the program would see revenues rise by an average of 12 percent, according to Kaiser.

“We’re being punished for having done Medicaid expansion,” said Colorado Insurance Commissioner Marguerite Salazar. “That’s what it comes down to, essentially.”

The Graham-Cassidy bill also targets Planned Parenthood. Specifically, it would eliminate federal funding for states to cover Medicaid family planning at Planned Parenthood clinics for one year — a provision likely to antagonize Lisa Murkowski (R-Alaska), who helped kill the last Senate repeal bill, and other moderates.

Murkowski’s support will be crucial if the Graham-Cassidy bill is going to have any chance of passage.

The biggest unknown is how many Americans would lose coverage if the bill is enacted. That’s because the Congressional Budget Office has said it doesn’t have time before the Sept. 30 deadline to assess how many people would be covered under the law.

Health care experts say it’s inevitable that more people would be uninsured given the measure’s funding cuts.

“States could do virtually anything,” said Larry Levitt, senior vice president for special initiatives at the Kaiser Family Foundation. “Anticipating what states will do with this money is a bit of a crapshoot.”

In the face of those and other questions, some conservatives are unhappy with the rush to pass the measure in the next week.

“I don’t think it’s anywhere near the promise of repeal we were given,” said Chris Jacobs, a conservative health policy analyst, arguing that Republicans could simply overrule the Senate parliamentarian’s deadline and keep working on repeal. “I reject the premise that this has to be done by Sept. 30.”

Jacobs, for one, is critical of the control that Washington would still retain over states under the measure since they would still have to seek waivers for their plans: “This is a corruption of the idea of federalism.”

Most Republicans, however, pooh-pooh the notion they’re acting irresponsibly to move forward quickly.

“I’d love to get an analysis from everybody who’s ever thought about health care, but we don’t have the time,” John Kennedy (R-La.), a backer of the bill, said earlier this week. “If I’ve learned anything in my time in government, [it] is that for every economist, there’s an equal and opposite economist, and they’re usually both wrong.”

None of the concerns about the Graham-Cassidy bill may ultimately matter, in any case, given the political imperative to repeal Obamacare.

“This is the last train out of the station,” said Joe Antos, a health policy analyst at the right-of-center American Enterprise Institute, who is critical of some parts of the measure. “If you’re not on it, what are the consequences?”

Adam Cancryn contributed to this report.