The nurses at Washington Hospital Center have voted to go on a one-day strike the day before Thanksgiving, the latest move in an increasingly contentious labor dispute at the region's biggest hospital.

A spokeswoman for National Nurses United, which represents the 1,600 nurses at the hospital, said 90 percent of those voting supported the one-day work stoppage. She declined to provide numbers. Voting took place Sunday through Wednesday.

Hospital officials said they were notified Thursday of plans for a potential one-day strike Nov. 24, in keeping with the required 10-day notice the union had to give management. The union said the strike would begin at 7 a.m. and last 24 hours.

Hospital officials have been preparing for a possible job action for several months, after the one-year contract with the nurses expired and talks broke down this summer.

In a statement, the union said it was staging the work action to protest unfair labor practices and to force management to negotiate a new agreement. The union says that chronic nurse understaffing is hurting patient care, which hospital officials dispute.

"Patients are our number one priority, and our number one goal with this strike is ensuring that they receive quality care," said Lori Marlowe, a nurse.

"We are disappointed that a union, new to this area and our hospital, has taken this step, and made untrue, unfair allegations about the quality of patient care at Washington Hospital Center," the hospital said in a statement. "We remain hopeful that differences can be resolved without a job action."

Officials said the hospital has a full contingency plan in case of a strike, anticipates no reduction in services and will remain open on a full schedule.

"We are fully prepared to take all necessary steps to meet our mission of providing safe, quality patient care," the hospital's statement said. "We hope that our nurses will choose to stay at the bedside to care for our patients. We are prepared, however, to bring in well-qualified and credentialed nurses to care for our patients."

The sides have been at odds over wages, benefits, staffing and other issues. In early October, managers imposed a wage plan that cut the shift differential for evening, night and weekend work. A few days later, the local nurses union voted to join National Nurses United, which has about 155,000 members and is the largest nurses union in the country. The union has been involved in one-day strikes at hospitals in Minnesota and Philadelphia.

On Nov. 1, the union filed a complaint with the District health department, asking officials to investigate what the union said were dozens of instances in 2010 of nurses caring for too many critically ill patients, resulting in compromised care.

Health department officials went to the hospital last week and sought staffing records for several different dates, which the hospital provided, according to Janis Orlowski, the hospital's chief medical officer.

In an interview Wednesday, Orlowski said the hospital has been unable to verify the "dramatic" incidents cited in the union complaint.

"A number of these are so preposterous," she said. "Our nursing managers are saying this did not happen."

If the incidents took place, they should not be difficult to verify because nursing managers are advocates for their staff, officials said. "If these scenarios happened, my door will be pounded," said Tonya Washington, interim chief nursing officer.

The incidents in the complaint are based on more than 500 reports that nurses have filed with the union since April 2009, saying they have worked without enough staff or have been directed by managers to work in a manner in which patient safety was at risk. The reports are called assignments despite objections, or ADOs.

The union is supposed to provide them regularly to the hospital's nursing officer, but Washington said she has not received any since July.