A mortise lockset apparatus (10) that includes a retractable bolt (20) movably supported within a case (12). A handle (18) is pivotally supported on a hub (16) supported in the case, the hub being operably connected to the retractable bolt. The bolt is retracted by turning the door handle. A lock-out mechanism (22) is configured to prevent the handle from being turned when the lock-out mechanism is in an engaged position. The handle lock-out mechanism also includes a cam (29) movably supported in the case and operably connected to a motor (30). A sliding stop (34) is movably supported in the case and is engageable with the handle hub to prevent the handle hub and the handle from turning. The sliding stop is also engageable with a cam surface (40) of the cam. The motor is configured to move the sliding stop by rotating the cam. The cam rotational axis (42) is disposed between diametrically opposed portions of the cam surface to minimize space requirements for the assembly.