SYDNEY — Australia's once-sluggish vaccination rollout has become a sprint as the nation tries to get ahead of its growing coronavirus outbreak. But the inoculation boom has also exposed a divide over when the country should abandon its pursuit of "covid zero" and lift lockdowns.

“Our goal [is] to live with this virus — not to live in fear of it,” Prime Minister Scott Morrison said Monday. He defended a plan to begin opening up once 70 percent of eligible Australians have been vaccinated, despite record cases in Sydney, and hinted that states that cling to lockdowns could face punishments.

“We have to break this cycle,” Morrison said of states going in and out of lockdown. “This groundhog day has to end.”

Australia wouldn’t be the first country to ditch a once-successful elimination approach because of the harder-to-suppress delta variant and increased vaccination coverage. Singapore, where about 80 percent of the population is vaccinated, has begun to drop quarantine restrictions for some travelers and is preparing further easing. And it may not be the last, as New Zealand also reckons with a delta outbreak.

But in Australia, covid zero became something of an article of faith. For much of the past year, the country was largely united behind the idea. Australians accepted snap lockdowns and two-week stints in hotel quarantine in an effort to eliminate the virus. And they shared in the success of a near-normal lifestyle envied around the world.

Yet, that unity has started to fray in recent weeks as fissures have opened between regions where coronavirus has taken root and those that remain relatively covid-free.

In Sydney, where a single case in mid-June has swelled to around 750 per day in the past week, state officials now stress living with the virus instead of eliminating it.

“I just urge people not to have the roller coaster of emotions of case numbers every day,” New South Wales Premier Gladys Berejiklian said Monday. “What is really important for us is to focus on getting the vaccine numbers up.”

Australia’s vaccination numbers are up, especially in New South Wales, where the number of shots administered per day has tripled since the outbreak began to one of the highest rates in the world. Some Sydney hot spots are vaccinating even more quickly. And on Tuesday, the state hit 6 million doses, allowing Berejiklian to reintroduce some minor perks later this week. She has said the state is on course to begin reopening by the end of October, if not sooner.

In the meantime, however, willpower is waning. Scores of people were arrested at two anti-lockdown protests in Sydney. Soldiers have been called in to help police with compliance checks and a dozen neighborhoods are under nightly curfew. On Sunday, a church in one hot spot held a service for 60 people, in which the pastor declared that “lockdowns are over in the name of Jesus.”

“We can’t live in isolation forever,” Berejiklian said. “We’re one of the few nations in the planet who is still living in isolation. But once you start opening your border, every state is going to see case numbers.”

For states with few or no infections, however, isolation still sounds pretty good.

In Western Australia, which reported zero cases Monday, Premier Mark McGowan has said his plan is still to “crush and kill” the virus, not live with it.

And in Queensland, where there were two new cases Tuesday, Premier Annastacia Palaszczuk said she may not open her state’s border with New South Wales even after the country hits a nationally agreed vaccination threshold.

As part of a national cabinet created to respond to the pandemic, both Palaszczuk and McGowan signed on to Morrison’s plan last month for a four-phase reopening, including reducing statewide lockdowns once 70 percent of eligible Australians are vaccinated. At 80 percent, statewide lockdowns will be eliminated and some international travel will resume.

But Palaszczuk said the “goal posts have changed” since then with Sydney’s outbreak obliterating the 30-case scenario envisioned by the plan.

“Now there are thousands,” Palaszczuk said Monday. “This is a book that hasn’t been written, folks. This is uncharted territory.”

The institute whose modeling underlies the four-phase plan insists hundreds of cases a day aren’t a hurdle to safely reopening at 70 percent.

The plan also says no state can relax its restrictions until the vaccination thresholds are met on a national level. Without major outbreaks to spur inoculations, Queensland and Western Australia have lagged behind other states and could delay a national reopening.

There is an element of politics involved, with the three state premiers to have raised concerns over the plan all belonging to the Labor Party. Berejiklian and Morrison are from the Liberal Party. The prime minister must hold an election early next year in which covid will be center stage.

Morrison has warned state and territory leaders against backing out of their “deal with the Australian people,” while his treasurer, Josh Frydenberg, has threatened to withhold some federal assistance.

But the state premiers aren’t the only ones to raise questions about the national plan. So, too, have some epidemiologists.

“It’s not based on logic,” said Mary-Louise McLaws, an epidemiologist and World Health Organization adviser. “It’s based on a model and models are often fraught with assumption problems.”

Among those problems, she said, is that the plan does not take into account the more-infectious delta variant.

But the biggest issue McLaws has with the plan is that it calls for opening up the country when 80 percent of people 16 and older are vaccinated. When you include children — who officials say appear to be more susceptible to delta than previous strains — that leaves roughly one-third of the country unvaccinated. A better strategy would be to focus on vaccinating at least 80 percent of 16-to-39-year-olds, who are most likely to catch and spread the virus, before reopening, McLaws argued.

The plan also means the nation could reopen when pockets — including more vulnerable Indigenous communities — remain undervaccinated, she said.

McLaws had advocated shutting down Sydney as soon as the first case of delta appeared in June. Instead, the premier waited 10 days.

With cases showing little sign of coming down, McLaws said she and Berejiklian agreed on one thing: Australia’s covid zero ambitions are over.