An energizable electromagnet of a door locking system is affixed to the door or the door frame for electromagnetically attracting an armature affixed to the other. A power control circuit is configured to selectively energize the electromagnet using a pulse-width modulated current cycle wherein two levels of magnetic force may be selectively applied to the system. A door position sensor is configured to provide a first communication signal to the power control circuit when the door is in a closed position. A second communication signal is provided when the door is not in the closed position. The electromagnet is energized at the lower level of magnetic force when the power control circuit receives the first communication signal and at the higher level of magnetic force only when an unauthorized attempt to open the door is initiated.