 -- The clock is ticking for Senate Republicans to be able to repeal and replace Obamacare — and follow through on their almost seven-year promise — through a special process that requires fewer votes. The deadline to pass the bill with a simple majority of at least 51 votes is Sept. 30.

For Republicans who worked around the clock in July to try to repeal the Affordable Care Act, also called Obamacare, it's deja vu. Sens. John McCain, R-Ariz.; Susan Collins, R-Maine; and Lisa Murkowski, R-Alaska, are on the fence once more about supporting the GOP's latest health care proposal.

This time, those Republicans are considering a very different option with a repeal effort led by Sens. Lindsey Graham, R-S.C., and Bill Cassidy, R-La.

What's familiar about the Graham-Cassidy bill?

As in previous Republican repeal efforts, Graham-Cassidy would immediately remove the individual and employer mandates to sign up for health insurance, two ACA requirements — with tax penalties for failure to comply — that have been unpopular with the public.

Graham-Cassidy would also repeal the medical device tax, which some said stifled medical innovations. The plan would repeal Medicaid funding for Planned Parenthood for one year, just as the "skinny repeal" was would have; would increase the amount that people may put into health savings accounts, or HSAs, which are popular with Republicans; and would allow people to use HSAs to pay for health insurance premiums.

An as with past repeal efforts, health insurance premiums for older and disabled Americans would go up, Medicaid expansion would be cut back, Medicare would not be changed, and cost-sharing subsidies, which reduce deductibles and co-payments, would be repealed in 2020.

What's different?

The Graham-Cassidy bill would give states more discretion with health care funds. Tax credits, Obamacare-era subsidies and Medicaid expansion dollars would be eliminated. Instead, states would receive block grants to allocate as they determine. How much money each state would receive would depend on a complicated formula that factors in population size and resident wages, and states would not have to spend money to increase health insurance coverage. Graham-Cassidy block grants would expire in 2026.

"It takes money that previously would have gone to premium tax credits and the Medicaid expansion and divides that up to states in a block grant, but the total amount of funding in those block grants is significantly below what would have gone through Medicaid expansion and tax credits under current law," said Matthew Fiedler, a fellow with the Center for Health Policy in Brookings' economic studies program.

"I think, with these block grants, there is going to be such intense uncertainty about what different states are going to do that insurers are going to get nervous and may hedge their bets even before 2020, maybe deciding the market is not worth it," he said.

The bill would cap Medicaid enrollment and funding, which could affect more than 60 million people. The plan would allow people over the age of 30 to sign up for catastrophic coverage plans — high-deductible, low-premium plans — in hopes that more healthy, young people will be covered.

Private market rules would remain the same, but states would be allowed to waive rating rules based on health status and age. States would be allowed to require working as a condition for Medicaid eligibility.

What parts of the Republicans' bill are controversial?

Because Graham-Cassidy's block grant plan would redistribute Medicaid funding, some states that applied for Medicaid expansion under Obamacare — including some red states — are concerned that their residents will lose out those funds and be saddled with very steep bills.

"If Graham-Cassidy passes, states will have less than two years to come up with a whole new health insurance program from scratch. And that will be a challenge even for the largest and best resourced states," said Larry Levitt, a senior vice president at the nonpartisan Kaiser Family Foundation.

While insurers would still required to provide health insurance coverage to everyone, Graham-Cassidy would allow states to apply for waivers to eliminate protections for people with existing conditions and to get rid of required coverage for essential health benefits, like maternity care, which could mean higher premiums for sick people.

But a major sticking point for lawmakers has been the rushed process to vote on the bill. Without a full report from the Congressional Budget Office, lawmakers won't know how much the legislation would cost or how many people could lose their coverage.

"Why did Obamacare fail? Obamacare was rammed through with Democrats' votes only," McCain said on CBS's "Face the Nation." "Are we going to ram through our proposal? ... That's not the way to do it."