The last time Senate Republicans tried to move forward on repealing the Affordable Care Act (ACA), it was Sen. John McCain, R-Arizona, who sunk the effort with a dramatic thumbs down. He may have done so again with the latest repeal plan, the Graham-Cassidy bill, announcing Sept. 22 he “cannot in good conscience vote” for the proposal.

“I would consider supporting legislation similar to that offered by my friends Senators Graham and Cassidy were it the product of extensive hearings, debate and amendment. But that has not been the case,” McCain said in a statement. “Instead, the specter of September 30th budget reconciliation deadline has hung over this entire process. We should not be content to pass health care legislation on a party-line basis, as Democrats did when they rammed Obamacare through Congress in 2009. If we do so, our success could be as short-lived as theirs when the political winds shift, as they regularly do.”

McCain offered similar legislative process concerns in July, when he voted in favor of opening debate on the repeal efforts. His somewhat surprising “no” vote which later followed seem to mark the end of repeal-and-replace efforts until last week, when the Graham-Cassidy bill to turn much of the ACA’s funding into block grants began to gain traction among Republicans and stirred up opposition among healthcare groups. Senate leaders had indicated a vote would be held ahead of the Sept. 30 deadline, not allowing time for a full analysis of the bill by the Congressional Budget Office—which played into McCain’s concerns because such an analysis would detail its impact on insurance premiums and coverage.

The momentum behind Graham-Cassidy appeared to have killed off talks in the Senate health committee involving both parties on short-term fixes for the ACA. In his statement, McCain encouraged those discussions to begin again.

“Senators Alexander and Murray have been negotiating in good faith to fix some of the problems with Obamacare,” McCain said. “But I fear that the prospect of one last attempt at a strictly Republican bill has left the impression that their efforts cannot succeed. I hope they will resume their work should this last attempt at a partisan solution fail.”

Sen. Rand Paul, R-Kentucky, had already announced his opposition to the bill because he feels it leaves too much of the ACA in place. With McCain also in the “no” column, its passage would require the support of every other Senate Republican, including Sens. Lisa Murkowski of Alaska and Susan Collins, who voted against several previous repeal attempts in July.

While both were officially undecided, Collins said earlier on Sept. 22 she was “leaning towards no” due to the bill’s provision that states could allow insurers to charge higher premiums based on a customer’s health status.

“The premiums would be so high they would be unaffordable,” she told the Portland Press Herald.

Besides the impact on people with pre-existing conditions, estimates by the Kaiser Family Foundation and Avalere Health said the bill would take billions in federal funds away from states which adopted the ACA’s Medicaid expansion and redistribute funds to those which didn’t. The Commonwealth Fund estimated it would result in 32 million more people being uninsured after 10 years, with up to 18 million more lacking insurance in the first year.