John McCain's no vote won't necessarily kill Graham-Cassidy health bill

• The GOP's Graham-Cassidy bill, being touted as the last-ditch effort for Republicans to replace Obamacare with a health care system of their own, is lurching towards a Sept. 30 deadline for a vote.
• The bill trades thoroughness for expediency under the guise of states' rights and replaces Affordable Care Act funding with block grants. That means 34 states – including those that expanded Medicaid under Obamacare – will see their funding greatly reduced.
• Consumers will almost certainly see rising premiums and health care costs but there are several other issues for concern.

How do you make a health-care bill the American Medical Association, AARP, Blue Cross, National Council for Behavioral Health, and more oppose? Ask Sens. Lindsey Graham and Bill Cassidy, whose Graham-Cassidy bill is being touted as the last-ditch effort for Republicans to replace Obamacare with a health care system of their own.

This isn't the first time the GOP has attempted to get rid of Obamacare this summer. So why doesn't it seem like they're learning any lessons? Because pursuing repeal through the Senate's reconciliation process means Republicans are more focused on the budget than actual health care policy, leaving huge unknowns for consumers.

That may be one reason John McCain just announced that he would not support the bill. A no vote from McCain puts the bill's survival in question, though it doesn't sink it entirely.

GOP health-care bills feel rushed – because they are

Republicans are trying to make health care changes through the budget reconciliation process, which requires a number of financial constraints. It leaves them with an easier path to passing a bill since they only need a simple majority to get the ball rolling. But it means they can't propose a policy that would impact deficits more than ten years out. Since health care is one-sixth of the American economy, that's hard to do. It also imposes an otherwise-arbitrary Sept. 30 deadline, meaning the health care aspects of their bills are rushed by design. That rule — the Byrd Rule — was first used in 1993 to block then-President Bill Clinton from passing comprehensive health-care reform through reconciliation; the Senate argued the scope of the bill's impact was too big to be approved through that process.

The Graham-Cassidy bill trades thoroughness for expediency under the guise of states' rights. The bill replaces Affordable Care Act funding with block grants. This might sound harmless enough on the surface, but it means 34 states – including those that expanded Medicaid under Obamacare – will see their funding greatly reduced.

One area where states would get more discretion under the bill involves their obligation to cover Americans with pre-existing conditions. States would be permitted to waive pre-existing condition protection as long as they still provide "adequate and affordable" coverage — but what qualifies as "affordable" is left undefined.

What will be the effects of these changes? Consumers will almost certainly see rising premiums and health care costs because subsidies are being replaced. There may be less coverage provided if states aren't able to do more with less, as Cassidy and Graham are purporting. But no one really knows the extent of the cost or coverage changes. Supporters of the bill are intentionally vague about what the effects will be, saying that states know better how to allocate money, that they shouldn't have Obamacare forced upon them, and, essentially, that we'll see what happens when it happens.

The bill's lack of specificity makes it hard to predict how it would affect consumers. There are few guidelines on how states have to allocate block grant money. "Adequate and affordable" coverage for consumers with pre-existing conditions is a concept that's so nebulous it's useless. The bill punts on the actual policy aspects, leaving a lot of questions. And those questions will remain, because there's no time to properly analyze it before the September 30 deadline.

The Congressional Budget Office has said it won't be able to fully score the bill before the deadline, so we're left with analyses from groups like Avalere Health and the Center on Budget and Policy Priorities. So far, none of the outcomes look good – and when you consider how and why the bill was created, it's no surprise.

The lack of specificity seems like a cynical attempt to fulfill Republicans' campaign promise of repealing Obamacare while absconding from any responsibility for its consequences.

Why Cassidy-Graham may very well pass

Still, Graham-Cassidy might have the Senate votes to move on. If reports are to be believed, it only needs a handful more "yes" votes to pass. John McCain's just released statement that he won't vote for Graham-Cassidy doesn't necessarily kill the bill because none of the other potential "no" votes feel like a lock.

Rand Paul voted for the last repeal bill after consistently threatening not to; Lisa Murkowski is reportedly being offered incentives for Alaska to vote yes; and Susan Collins has stayed mostly quiet, so far saying only that she's "leaning no." While McCain's statement makes the bill's chances of passing slimmer, we've learned time and again during this process that it's not over until it's over.

Why? First, funding changes fall partly along party lines. States like New York and California – those that expanded Medicaid – will lose funding but would have been unlikely to vote for the bill anyway. Meanwhile, states like Alabama would see additional funding. The bill relies on enough Republican Senators voting with their party, and enough Senators from "bubble states" seeing alleged gains, to win the support it needs.

Perhaps more to the point, this is the Republicans' self-imposed last chance to rid themselves of Obamacare. Of course, it isn't actually their last chance – even after September 30 they'll control both Houses of Congress and the presidency – but it's the last chance to pass it with a simple majority. And they've backed themselves into a corner with their base. The GOP was humiliated, sometimes by its own president, over the summer for its health care failures. Passing something, anything, at the eleventh hour would help the party save face and move on to other matters.

But there's danger in passing a bill that has had essentially no vetting. If the independent analyses of the bill are to believed, Graham-Cassidy will leave millions of Americans without health insurance.

Should Republicans start treating their health-care bills like health-care bills — focusing on health outcomes rather than solely on budgetary procedures — they would be better able to get the backing of the public, industry groups and crucial members of their own party.

Commentary by Jennifer Fitzgerald, the CEO and co-founder of PolicyGenius, an independent digital insurance company for consumers. Previously, she was a junior partner at McKinsey & Company where she advised Fortune 100 financial services companies on marketing and strategy. She is a graduate of Columbia Law School and Florida State University. Follow her on Twitter @jenlfitzgerald.

For more insight from CNBC contributors, follow @CNBCopinion on Twitter.

WATCH: McCain explains his decision on Graham-Cassidy