Santa Rosa Memorial Hospital nurses went on strike Monday for the third time since October, launching a two-day walkout to protest the direction of labor talks.

Hospital management and the Santa Rosa-based Staff Nurses Association accused each other of refusing to compromise in ongoing labor negotiations.

The first nurses formed a picket line after their shift ended Monday morning at 5 a.m. Later in the morning, about two dozen nurses joined the picket line in front of the hospital on Montgomery Drive.

"We've been negotiating and we've made progress on some issues, but not on the critical issues," said Sue Gadbois, president of the nurses union, which represents about 650 nurses.

Gadbois said outstanding issues include disagreements over staffing, job security, benefits and pay. She said the hospital is proposing significant increases to health insurance contributions, in some cases doubling or tripling premiums.

Debra Miller, vice president of human resources for St. Joseph Health in Sonoma County, which runs Memorial Hospital, said the hospital has backed off an initial proposal to increase benefit contributions paid by full-time nurses.

Instead, the hospital is now seeking to increase benefits contributions paid by part-time nurses. Miller said the hospital's annual contribution to health benefits for two part-time nurses is almost double what it would pay for one employee working the same number of hours.

Miller pointed out that Memorial Hospital, along with every other hospital in the nation, will be getting significantly less money in government reimbursements because of budget agreements related to the fiscal cliff and full implementation of President Obama's health care overhaul in 2014.

"We need to get our costs down and the lion's share of our costs is labor," Miller said.

But the nurses union argues the hospital has a healthy operating margin, which it says could be used to hire more staff and increase wages.

The nurses union has insisted that its main concern is patient safety and adequate staffing levels. It has made several staffing proposals, including hiring a specialty float nurse for the night shift, designating break relief nurses to cover meal breaks and establishing staffing levels in accordance with the level of illness of patients.

The hospital says it already has specialty nurses assigned to work the hospital during the night shift; fellow nurses cover those who take meal breaks; and the existing contract already abides by state rules for minimum nurse-to-patient ratios, including those that take into account the severity of a patient's illness.

Also, nurses want an 8 percent wage increase over the period of the contract, while the hospital proposes a 4.5 percent increase.

Hospital officials have said the average nurse makes about $100,000 annually, but many union representatives dispute that figure.

Kery Poteracke, 37-year Memorial Hospital nurse who is part of the negotiating team, said that nurses salaries are "all over the place" and many make much less than the average calculated by hospital management.

Poteracke said that a starting nurse on day shift makes $45.31 an hour, and that after 25 years that same nurse will make $63.95 an hour. A starting nurse working the night shift would make $56.63, and after 25 years would make almost $80 an hour. There are many part-time nurses who don't make anywhere near $100,000, she said.

"My daughter is a nurse at the hospital and she makes $45,000," Poteracke said. "The executive management team make well over $300,000 to $700,000 and above. And at this point they have not offered to take a cut in pay."

Since the second strike, the hospital has proposed having more flexibility for canceling regular nurses' shifts whenever it is overstaffed, Gadbois said. In such cases, the hospital currently cancels shifts for "traveling nurses" before it cancels regular nurse shifts.

Miller said that shifts for contracted traveling nurses, who often cover leaves of absence, can be canceled a certain number of times. After that, the traveling nurses must be paid whether they are needed or not.

"We want to have the flexibility to cancel another nurse since we have to pay for the traveler," said Miller.

The union said hospital administration is also proposing changing language in the contract that would allow it to not pay overtime to nurses who work more than 8, 10 and 12 continuous hours if those periods extend beyond the regular workday.

Miller rejected that claim and said the hospital is simply trying to update the contract language and make it consistent with existing wage laws.

Memorial nurses approved a two-day strike, but they won't be able to return to work until Friday because the agency providing replacement nurses requires a four-day commitment, hospital officials said.

Some nurses at Petaluma Valley Hospital, who are represented by the California Nurses Association, temporarily set up pickets Monday in support of the striking Memorial nurses but remained on the job.