A keyless door latch system for doors of motor vehicles includes a backup electrical power supply to unlock the door latch in the event the primary power supply fails, thereby eliminating the need for a lock cylinder. The latch system includes a user input device having first and second user input features. The door latch system is configured to supply electrical power from the primary electrical power supply to unlock the latch upon actuation of the first user input feature, and to supply electrical power from the backup electrical power supply to unlock the latch upon actuation of the second user input feature. The user input device may comprise a wireless portable device that generates first and second wireless signals upon actuation of the first and second user input features, respectively.