Wichita ? A union-initiated cost-cutting effort to persuade Raytheon Aircraft Co. not to send electrical work to Mexico may have failed.

Raytheon officials said Thursday they’ve tentatively decided to transfer work now done in its wire harness department in Wichita to an outside supplier. The announcement left doubts about retention of 350 employees at the Wichita plant.

“The market conditions are forcing us to reduce … costs in all parts of the business,” spokesman Tim Travis said.

He said Raytheon was proceeding on negotiations with potential suppliers, declining to name the candidates.

A company study obtained in March said Raytheon was looking at the capabilities of at least two manufacturers in Mexico — Aerotec in Chihuahua and Suntron in Tijuana.

By terms of the company’s labor agreement, the Machinists union now has 30 days to try to persuade the company to keep the work in Wichita.