The nurses, represented by the Massachusetts Nurses Association, returned to the bargaining table Monday morning with Mass General Brigham executives and a federal mediator. As of Monday afternoon, the session was still ongoing and no breakthrough had been announced.

"We attended the start of the negotiating session between MGB and the nurses today to urge both sides to stay at the table and continue working toward an agreement," Healey and Wu said in a joint statement. "Important progress was made the last time they were at the table together, and they need to continue to push forward toward a resolution that makes sure our nurses receive a fair contract and avoids a strike for the sake of the patients and families who depend on them."

The union issued a notice on Nov. 1 for an open-ended strike, amping up pressure ahead of Monday's high-stakes meeting. The nurses had been prepared for an indefinite strike in mid-October, but union leaders paused that plan to allow members to vote on what MGB described as its "last, best and final" contract offer. Nurses ultimately rejected the offer.

The MNA says nurses are seeking limits on the use of temporary nurses, affordable health insurance, and a wage scale that is "competitive for new and experienced nurses and helps with the recruitment and retention that the hospital needs to provide world-class nursing care." The union has accused MGB of leaving out a core demand for cost-of-living increases from its final offer.

In a media alert Friday about the looming strike, MGB said its final offer had "reflected movement in response to priorities raised by the MNA bargaining committee" and that nurses would continue to be "among the highest-paid locally, statewide, and nationally." MGB said its offer incorporates existing 5% annual raises for nurses moving through the 20-step wage scale, plus increases to base wages and new raises for nurses at the top step.

The Brigham will stay open during the potential strike and bring on temporary nurses to maintain continuity of care. MGB says the "majority of these nurses provided care during the July work stoppage and are familiar with the Brigham and our healthcare system." Department of Public Health surveyors will be at the Brigham daily during the possible strike to monitor patient care, according to MGB.

Healey's involvement Monday follows an unsuccessful attempt to avert the Brigham nurses' strike in July. Judith Shindul-Rothschild, a Boston College research professor and former MNA president, said elected officials in Massachusetts lack the clout that the late U.S. Sen. Edward Kennedy once brought to healthcare labor disputes.

"Sen. Kennedy had the capacity to have those issues settled in a way that left everybody leaving the negotiations feeling like their voices were heard," Shindul-Rothschild said. "And I just don't see anyone, frankly, in our elected officials — both in Congress, in the Senate, and in the State House — that has that kind of clout, and I think that's why we're sort of whistling in the wind here."

Shindul-Rothschild said the rise of travel nurses, compounded by the "corporatization" of healthcare, has created new flashpoints for the Brigham nurses. But she insisted nurses overwhelmingly tend to walk off the job in pursuit of protecting patient care in the long term.

"I really think that the leaders in this state need to force the parties to come together for a conclusion," Shindul-Rothschild said. "And I don't know if they're tiptoeing around lightly, around Mass General Brigham, because of the stature of Mass General Brigham."

Steve Striffler, director of the Labor Resource Center at the University of Massachusetts Boston, said it appears the parties have made a "genuine effort to bargain," though he acknowledged that MGB has "drawn a line in the sand" around cost-of-living issues.

"Both sides, or certainly MGB I think, in particular, has been very stubborn at the table and hasn't moved ... but that's also their right," Striffler said. "But I think there is kind of an expectation, though, that there would be some movement on these issues, and MGB has moved very little."

Maria O'Brien, a Boston University School of Law professor who teaches employment law, said the Brigham dispute reflects broader economic trends facing employers and workers, including rising inflation and health insurance premium spikes that are outpacing wage growth. Healthcare executives are also preparing for federal Medicaid changes and funding losses, she said.

"All of the parties here, it seems to me, are under pretty extraordinary pressure right now," said O'Brien, who described the situation as "unusually acrimonious."

The strike would be the second major work stoppage at the Brigham this year, following a July strike. A prolonged walkout could strain patient care across the Longwood Medical Area and ripple through the region's healthcare system.