Unionized nurses have authorized a one-day strike at the University of Chicago Medical Center, their leaders said Friday.

Members of the National Nurses Organizing Committee/National Nurses United voted overwhelmingly Thursday night to authorize the one-day strike, said Talisa Hardin, chief nurse representative for the union. The vote does not mean a walkout will occur, but it authorizes the union’s bargaining committee to call one.

Under the law, the union must give the hospital at least 10 days notice of any strike. NNOC/NNU, which has 2,200 workers at the U of C Medical Center, is negotiating to replace a four-year contract that expired in April.

In a statement, the hospital said it was disappointed in the vote but would continue to bargain in good faith. “We have a full strike plan in place to ensure our patient care will continue should the union call for a walkout in the future. This includes engaging an outside firm that can provide a fully trained group of nurses to provide continuity of care,” the hospital said.

Hardin said unresolved issues include staffing levels because nurses are being forced to care for too many patients. She said the union also is asking for better security measures. As for wages, “We haven’t come to an agreement,” she said.

About 75% of members participated in the strike vote and 98% of those voted in the affirmative, Hardin said. She said bargaining sessions are scheduled for next week.

Marti Smith, midwest director of the union, said it typically favors a one-day strike as an initial tactic before seeking an open-ended walkout. “A one-day strike provides maximum impact on the hospital but minimal impact on patients,” Smith said.

She said the hospital could rely on administrative staff to help patients during a one-day strike and would not need to bring in outsiders.