It’s a plot twist steeped in irony: A health emergency for a Republican senator throws the party’s health care plan into jeopardy.

Senate Majority Leader Mitch McConnell was prepared to put the Republican health care bill on the floor this week and dare his wavering caucus to vote it down. Then a health emergency forced John McCain into surgery over the weekend, and the whole plan went out the window.

Without McCain to vote in favor of the Better Care Reconciliation Act, the Republican plan to repeal and replace Obamacare, Republicans don’t have enough votes to pass it. So the months-long Republican slog to repeal and replace Obamacare will drag on another week — and maybe more.

That’s bad news for the bill’s supporters. The longer the Senate waits to vote, the more likely it becomes that a third senator will defect and kill the bill entirely.

McConnell has been pressuring skeptical senators not to publicly speak out against the bill, as Sens. Rand Paul and Susan Collins, the two Republican defectors, already have. The extra week gives him time to cut deals. But it also gives the bill’s opponents time to get a critical third opposing vote, as the plan’s devastating consequences become more clear.

“McConnell clearly got his members to agree to stay quiet,” one Republican health care lobbyist told me. “How much longer can he enforce that? This entire week? Longer? It can’t last, and when it breaks, there may be a flood.”

McCain’s blood clot means McConnell doesn’t have the votes

McCain’s office announced over the weekend that he had surgery on Friday night to remove a blood clot above his left eye. The senator would remain in Arizona for the next week to recover, his office said. Soon after that news broke, McConnell announced that he would delay the vote on the health care bill until McCain returned.

McConnell needs 50 votes to open debate on the bill and eventually pass it. If McCain isn’t present, he only has 49. The Arizona senator has been telling reporters in recent weeks that he would vote to start debate, even if he still had concerns about the underlying bill.

This is the second time Senate leadership has delayed a vote on the bill. Before the July 4 recess, McConnell conceded he didn’t have the votes.

McConnell and his compatriots have been pressing senators to at least let debate begin on the bill, the first step in a multi-step process to final passage. They were making the case that Republicans had campaigned for years to repeal and replace Obamacare with something — and this bill was their something.

They sounded ready to take the risk of putting the legislation on the floor and hoping the pressure of delivering on that promise would carry the day. But McCain’s absence has put that plan on hold, leaving legislation with abysmal approval ratings to twist in the wind.

“I feel like it hurts,” another health care lobbyist told me of the delay. “Loss of momentum.”

Supporters and opponents of the bill will be tugging on the critical swing votes

A half-dozen senators have serious concerns about the health bill. Most of them — Sens. Shelley Moore Capito, Rob Portman, Dean Heller, and Lisa Murkowski — are worried about the $772 billion in Medicaid spending cuts. Sen. Mike Lee (R-UT), one of the most conservative members, still isn’t sure he’s satisfied by the plan’s unwinding of the health care law’s insurance regulations.

Any one of those senators could be the 51st vote to kill the bill. The consensus among health care lobbyists was that the longer the vote is postponed, the less likely the bill is to pass. “Time hurts Senate GOP leadership,” a third Republican health care lobbyist said.

During the delay, the bill’s critics will step up their resistance. They seem likely to target Heller. Nevada’s Republican governor, Brian Sandoval, has been a fierce critic of the Senate bill, and many believe Heller won’t be able to vote for it if the overwhelmingly popular Sandoval opposes it. He also faces the toughest reelection race of any Senate Republican next year.

The critics will likely have more analysis to back them up. The media and outside advocates will have more time to untangle the consequences of the proposal. On Friday night, the top health insurance lobbying groups said the measure could send premiums skyrocketing for people with preexisting medical conditions, a statement likely to make many middle-of-the-road GOP senators uncomfortable.

And at some point, the Congressional Budget Office will release its latest analysis of the legislation. A new report was supposed to come out on Monday, but that has now been delayed, according to Senate Republican aides. That analysis will still likely show that the bill would lead to millions fewer Americans having insurance compared with Obamacare.

Still, McConnell also has more time to cut deals to keep the swing votes on board. The legislation already includes provisions targeted to Alaska, likely intended to convince Murkowski to back the bill. Leadership has also added $45 billion directed to the opioid crisis to try to assuage Capito and Portman’s concerns about the Medicaid cuts.

McConnell could still add more money — rough estimates suggest as much as $100 billion — once the Congressional Budget Office has estimated how much money the bill will save the federal government. And the Republican plan has overcome delays and setbacks before. The House infamously pulled its bill minutes before an expected vote, but pulled back together a month later, once the furor had faded, to pass the legislation.

So that tug of war will only intensify — an extra week for the raucous debate about the Republican plan for overhauling the nation’s health care to heat up. It could be even longer: The New York Times reported that McCain might not be able to return for two weeks, if not more.

Given the political math, McConnell cannot move forward until McCain returns. This is a critical moment for Senate Republicans. “Everyone has been in crisis mode since early March, and having the deadline pushed back again and again is exhausting,” the first Republican health care lobbyist told me. “People make mistakes when they are exhausted, or take the easy path out. Something to watch.”