A multi-mode powertrain system including an internal combustion engine, a high-voltage electric machine and a high-voltage electric power system is described. A method for controlling the multi-mode powertrain system includes, in response to an operator initiating a jumpstart, electrically connecting the high-voltage electric power system to a remote electric power source and energizing contactors between the high-voltage electric power system and the remote electric power source. Electric power flow through an auxiliary power module electrically connected to the high-voltage electric power system that supplies electric power to an accessory device is minimized. Engine starting parameters are modified, and the internal combustion engine is started by controlling, via a controller, the high-voltage electric machine to spin the internal combustion engine, and controlling operation of the internal combustion engine based upon the modified engine starting parameters to effect starting.