The Raiders confirmed the signing of running back Michael Bush Wednesday as well as the releases of safeties Jarrod Cooper and Darnell Bing.

Cooper’s status was in jeopardy from the moment it was announced he had received a four-games suspension for violating the NFL’s steroid policy.

The release of Bing, a fourth-round draft pick out of USC last season, came as at least a mild surprise.

The Raiders attempted to make Bing a weakside linebacker after a career as a safety at USC. He was placed on injured reserve following a neck injury during the preseason.

Bing was moved back to safety when Lane Kiffin came aboard, and he seemed to make his share of plays during OTAs and minicamps.

Kiffin, when asked about the shift of Bing during the offseason, said simply and without enthusiasm it was Bing’s best chance to make the team.

The exit of Cooper and Bing reduces the glut at safety. Remaining on the training camp roster are 2006 starters Michael Huff and Stuart Schweigert, veteran free agent acquisitions Donovin Darius, Colin Branch and B.J. Ward, holdover Hiram Eugune and rookie fifth-round draft pick Eric Frampton.