A nursing union at the second largest hospital in Maine is planning to strike over what it alleges are dangerously unsafe staffing levels.

The Maine State Nurses Association, National Nurses Organizing Committee and National Nurses United contract with Eastern Maine Medical Center in Bangor was set to expire on Thursday, and bargaining teams representing the union and the hospital were resuming recently stalled negotiations. Spokespeople for the union and the hospital said the union gave notice Thursday that members plan to strike on July 13 and 14.

Cokie Giles, a nurse at the hospital and president of the Maine State Nurses Association, said the hospital’s staff of 834 union nurses needs to be closer to 930. Hospital officials said the facility has a total of about 1,200 nurses.

“Nurses don’t want to put in a strike notice, but we have got to get some relief for the nurses that are on the floor,” she said.

The hospital’s chief nursing officer, Deborah Sanford, said the hospital’s ratio of nurses to patients is in line with national guidelines. She said the nurses’ decision to strike was also motivated by compensation issues that remain on the table.

Meanwhile, hospital representatives said the facility is preparing for the nurses’ strike. The hospital will have replacement nurses working at the hospital for four days beginning on the morning of July 13, said Deborah Carey Johnson, the president and chief executive officer of the hospital.

Having the replacement nurses for multiple days will minimize disruption for patients, she said. EMMC nurses also conducted a strike in 2010.

“The choices we make now have real consequences, and we must ensure we’re doing what’s best for our patients and the communities we serve,” Johnson said. “We insist on focusing on the issues that actually affect our patients, nurses and our hospital.”

The two sides extended the contract in mid-June when it was previously about to expire.

Eastern Maine Medical Center is the largest hospital in central part of the state, and the second-largest overall after Maine Medical Center in Portland.