A hybrid powertrain system includes an electric machine, a torque converter, a transmission, a hydraulic pump, and a controller, and it is arranged to transfer mechanical power to a driveline. The torque converter includes a clutch, a pump, and a turbine, and the electric machine is rotatably coupled to the hydraulic pump and to the torque converter pump. The hydraulic pump is fluidly connected to the transmission, and the controller is operably connected to the electric machine and the torque converter clutch. The controller is executable to determine an operator command, and control the electric machine to spin the hydraulic pump in a speed control mode and control the torque converter clutch in an open state. Upon achieving a desired minimum pump speed, the torque converter clutch is applied in a slip state and the electric machine is controlled in response to the operator command.