Union employees are set to strike Deaconess Medical Center and Valley Hospital and Medical Center today in a one-day action as contract negotiations lag.

Negotiations were still in progress with a federal mediator late Tuesday. As of 10:30 p.m., a deal had not been reached.

Deaconess spokeswoman Julie Holland said both hospitals have hired replacement workers who will fly in to Spokane to cover shifts, and neither facility has altered its surgery schedules or other services.

The two hospitals employ 2,300 employees. About 950 are represented by the Service Employees International Union 1199NW.

The organized workers have been without a contract since December 2008.

The stalemate has turned increasingly contentious, with the union pressing a series of unfair labor practices complaints against the hospitals and their corporate owner, Community Health Systems Inc. The Tennessee-based company is the nation’s largest for-profit hospital operator.

SEIU 1199NW is based in Seattle and is the largest health care union in Washington.

The National Labor Relations Board is now arguing those complaints on behalf of the union. A trial in front of an NLRB administrative law judge has been postponed as the sides continue to negotiate.

The striking workers at both hospitals include respiratory therapists and radiological, ultrasound, medical laboratory and surgical technologists. Service workers include health unit coordinators, nursing assistants, food service workers and housekeepers.

Registered nurses will be on strike at Valley.

Registered nurses at Deaconess Medical Center left the union two years ago and are expected to work their shifts today. So are other nonunion employees including physicians and managers.

The strike is not expected to be contentious. Both sides say they want to avoid disruptions to patient safety and care.

The hospitals released a media statement indicating that extra security officers have been hired to ensure access to the hospitals.