Union nurses at Crozer-Chester Medical Center in Delaware County went on strike Sunday morning in a dispute that involves pay, pensions, and staffing levels.

Wearing red T-shirts, nurses picketed on the hospital perimeter in Upland while replacement workers from the Colorado staffing agency U.S. Nursing Corp. did their jobs inside.

The hospital, which has taken an aggressive marketing stance against the strike, maintains the fight is about money. Saying it is in financial trouble, it has proposed cutting pay for its most senior nurses and switching to a less-lucrative retirement plan.

The nurses maintain the battle is about inadequate staffing levels and other working conditions. Their union, the Pennsylvania Association of Staff Nurses and Allied Professions (PASNAP), has proposed a pay freeze for the next year.

Grant Gegwich, a Crozer spokesman, said the typical full-time nurse at the hospital makes $103,000 a year. Bill Cruice, the union's executive director, said the average was $84,000, but that includes part-timers. He said pay at Crozer-Chester was comparable to what nurses in other Crozer system hospitals make.

The 565 union members worked under the terms of their old contract after it expired June 8. The strike began at 7 a.m. Sunday. The hospital maintains there are 535 union members.

The union had planned a two-day work stoppage. The hospital then announced it would fill the nurses' shifts with replacement nurses for three additional days.

Gegwich declined to say how many new nurses had been hired but said, "We have enough replacement nurses to continue to provide excellent staffing on all units."

The hospital will operate its emergency department, operating rooms, critical-care, and medical surgical units, pediatrics, psychiatric, and home-care services during the strike, he said.

The next bargaining session is scheduled for Tuesday .

Cruice said the proposed cuts of $2 to $4 an hour would affect nurses making $50 an hour and up. More drastic cuts have been proposed for nurses who are paid extra to work every weekend.

The proposal to switch from a defined-benefit plan - a retirement plan that guarantees a certain income level - to a defined-contribution plan - one with a set level of contributions but payouts that may fluctuate with the market - follows a long-standing trend among employers. Cruice said Crozer's suggested 401(k) would be underfunded.

"From our perspective," he said, "the form of the benefit is less important than the amount of the benefit."

About 100 nurses at a time took shifts marching within sight of a sign on the parking garage thanking employees for donating $330,000 to renovate the emergency department. Many drivers honked as they passed, and the group got support from a University of Pennsylvania nurse who handed out cookies, a Republican politician running for state representative, a very tall Teamster in a sleek blue suit, and a local caterer who gave out hot dogs.

Nurses on the line repeatedly said they were worried about staffing, the degree to which they are expected to multitask, and problems with getting supplies when they need them.

"The biggest issue for me is staffing," said Elaina Adams. "It's staffing, hands down."

She came with cellphone photos taken Sunday morning by someone inside the hospital of empty supply bins for urinals, mouth-care supplies, and saline.

Asked whether things were so bad they wouldn't go to the hospital themselves, several nurses said no.

"The nurses are great. The doctors are great," Adams said. "It's the administration that needs to step back and look at what they're doing."

Gegwich said that Crozer-Chester's staffing levels were average or above and that it spent more on nurse staffing "than any comparably sized hospital in the area."

He said the nurses had seemed more interested in money during contract talks. "Bargaining sessions have focused overwhelmingly on economic matters such as wages, benefits, and costly pay premiums," Gegwich said.

215-854-4944 @StaceyABurling