Nurses voted Wednesday to authorize a second strike at 16 hospitals in the Twin Cities and Duluth areas, then shocked hospital leaders Thursday by immediately scheduling the walkout.

As many as 15,000 nurses will leave hospital bedsides Dec. 11, unless they can come to terms on pay, workplace violence prevention and staffing levels. The strikes would end Dec. 31 at most hospitals but continue indefinitely at St. Luke's hospitals in Duluth and Two Harbors.

Nurses drew a direct line between understaffing and hospitals being overwhelmed this flu season. Five nurses were caring for 39 patients one night on a cardiac unit in Essentia Health's St. Mary's Medical Center in Duluth, an 8-to-1 ratio that is excessive even on overnight shifts, said Essentia nurse Corrine Schraufnagel.

"We are stretched incredibly thin at the hospital," she said. "It is dangerous and scary some shifts — the care that some of the patients are receiving."

Hospital leaders agreed that staffing levels are low, particularly amid an unprecedented early season surge in influenza and a spike in RSV that has used up pediatric inpatient beds. Only six of 144 pediatric intensive care beds were open Monday statewide, and leaders at Children's Minnesota said capacity will take a severe hit if the strike occurs.

Children's has recruited 300 replacement nurses so far to take over during the strike for a usual complement of 1,000 at its hospitals in Minneapolis and St. Paul. Children's leaders said they already are planning to transfer critically ill children out of state, because its ICU capacity is expected to drop from 62 to 33 during the strike.

"This is the worst possible time for the union to call for a strike that would pull nurses away from the bedside," said Dr. Marc Gorelick, Children's chief executive. "If this work stoppage materializes, it's going to put kids in danger, and that's why we're putting out the alarm."

The result of the vote was anticlimactic; unions don't call for strike votes unless they have support — just as MNA did this fall when a similar vote led to a three-day strike of about 15,000 nurses. MNA had already surveyed members about next steps this winter.

The immediate strike notice was a surprise, though, deviating from a successful strategy in 2019 when a strike vote alone by Children's nurses resulted in accelerated negotiations and a deal two days later.

Understaffing problems have worsened, with many nurses leaving hospitals after the worst of the pandemic, said Angela Becchetti, an Abbott Northwestern nurse and MNA board member. The lack of compromise on ways to retain nurses and boost staffing motivated the quick decision to strike — and the decision by St. Luke's nurses to go a step further and make their strike open-ended.

"It's time," Becchetti said. "Nine months at the [negotiating] table, we have gotten nowhere on staffing."

Negotiations continued Thursday, but hospitals also pivoted and started hiring replacement nurses at rates that far exceed typical wages. Gorelick said Children's would use its regular nurses in the event of a last-minute deal, even though it has already financially committed to replacement staffing.

Children's is involved in the contract talks along with Allina Health's Abbott Northwestern, Mercy and United hospitals, North Memorial Health in Robbinsdale, HealthPartners' Methodist Hospital in St. Louis Park, and M Health Fairview's Southdale and St. John's hospitals along with the West Bank campus of the University of Minnesota Medical Center.

Essentia hospitals in Duluth and Superior are also involved along with the two St. Luke's hospitals. Contracts are reached between MNA nurses and their individual hospital systems, but the negotiations take place concurrently.

A statement from several of the negotiating Twin Cities hospitals urged people to call 911 or go to emergency rooms during the strike if they have serious health needs. Others with less critical needs "may experience longer wait times for services while care teams triage patients," the statement said. "We ask everyone for patience."

Negotiations have progressed since the fall strike, when nurses wanted more than 30% raises over three-year contracts and hospitals offered about 10%. At Methodist and North Memorial, the nurses now are asking for 20% raises and the hospitals are offering 14.5%.

Some hospitals have reached tentative agreements with nurses on how to improve safety, with assaults by patients and visitors on the rise. Staffing plans are another issue — with nurses wanting more assurances of adequate nurse-to-patient ratios than hospitals are willing to give.

MNA negotiators initially asked for the ability to reject staffing plans if a majority of nurses viewed them as unsafe. Hospitals balked at relinquishing so much control. Nurses have since asked to automatically review and revise staffing levels if patient falls, bed sores or other preventable problems significantly increase.

Gov. Tim Walz on Thursday said he is "incredibly hopeful" the two sides will work out a deal that gives nurses enough resources while not compromising hospitals' finances.

"I know now that there's a lot of tensions around health care in general, and these providers that have been on the front lines are feeling that strain," he said.

Staffing has been a core concern in prior contract talks, and prompted a one-day strike in 2010. Solutions were set aside in a final deal that year that preserved pension and other benefits. Methodist and Southdale nurses leaving a voting site in Bloomington on Wednesday said that staffing solutions can no longer be bargained away.

Southdale medical-surgical nurse Nellie Arsenyeva said she loves her hospital and patients, but she is routinely picking up four-hour extra shifts after 12-hour regular shifts because of shortages. Pressure has increased over the past two years to take on extra patients, even those with complex illnesses or obesity levels that make them difficult to transfer.

"It's hard," she said. "We're overworked."

Staff writers Jana Hollingsworth and Ryan Faircloth contributed to this report.