CHICAGO (CBS)– The University of Chicago is gearing up for a possible nurses strike this Friday.

The hospital is on diversion, meaning ambulances are being asked to go to other hospitals.

Hospital administrators say they’ve transferred about 10 to 15 patients–all children–to other hospitals.

The U of C Medical Center says about 630 reserve nurses are on standby.

Contract negotiations are still going on.

National Nurses United says resources are stretched thin and they want the hospital to beef up the nursing staff. The hospital argues they are already well-staffed.