It's do or die this week for the healthcare bill from Sens. Lindsey Graham (R-S.C.) and Bill Cassidy (R-La.) to overturn the 2010 Affordable Care Act, aka Obamacare.

A summary of the revised Graham-Cassidy bill reveals increased funding of block grants to some states to attract support from Sens. Lisa Murkowski (R-Alaska) and Susan Collins (R-Maine), according to The Washington Post. State block grants would replace federal funding under the GOP's latest bid to repeal the ACA.

All past Republican efforts to overturn former President Barack Obama's signature healthcare law have failed, and prospects for Graham-Cassidy are fading fast.

Murkowski and Collins have withheld their support of the Graham-Cassidy bill over concerns in part that changing the ACA funding structure from Washington-directed to state-controlled would cut Medicaid spending on healthcare for low-income Americans. They also voted against their party's previous try to repeal Obamacare.

Currently, Republicans hold a 52-48 advantage over Democrats in the Senate. Graham-Cassidy faces a Sept. 30 vote deadline for the majority party to prevail with 50 votes plus that of Vice President Mike Pence versus a 60-vote threshold afterward.

President Donald Trump took to Twitter to urge passage of Graham-Cassidy over the weekend. However, intraparty turmoil puts the approval of Graham-Cassidy in question as Sens. Rand Paul (R-Ky.) and John McCain (R-Ariz.) oppose the bill.

Meanwhile, Sen. Ted Cruz (R-Texas) has also expressed doubt that he will vote for it. Senate Democrats all oppose Graham-Cassidy.

Further, 52 percent of Americans oppose the bill, according to a CBS News poll taken Sept. 21-24. Graham-Cassidy also faces unified opposition from U.S. doctors, health insurance plans and hospitals. They warn that Graham-Cassidy's spending cuts to Medicaid and more costly insurance premiums will harm consumers and patients.

According to Health Access California, a consumer advocacy group, the bill "undoes all the patient protections of the ACA, by allowing states to set their own rules, or no rules — with no federal requirements to abide by standards or policies such as no lifetime limits on coverage, no discrimination based on pre-existing conditions, essential health benefits, or other policies.

"Without the funding, even states like California would be under enormous pressure to lower premiums by scaling back benefits and consumer protections."

In the decade before the ACA became law (which includes the Great Recession of 2007-09), about 15 million Americans lost employer-based healthcare insurance, according to Josh Bivens, research director for the Economic Policy Institute in Washington, D.C. By contrast, under the ACA from 2010-15, 19.2 million people gained healthcare coverage.

The bill could improve the ACA with certain changes in policies, according to the Washington, D.C.-based Heritage Foundation.

However, the senators may not know what outcome to expect. The nonpartisan Congressional Budget Office plans to release a preliminary report on the full scope of Graham-Cassidy this week. As a result, the bill's Sept. 30 vote deadline ensures that senators will not have a complete CBO analysis to guide them.

One thing is clear for this healthcare bill. The clock is ticking, and there is no sudden-death overtime option in sight.