The present invention provides a method adapted to control a hybrid electric vehicle having a primary power source and a secondary power source. The method includes estimating the power capability of the primary power source, and thereafter obtaining a power command from the vehicle's driver. A primary power demand and a secondary power demand which collectively meet the driver power command are then established, and a desired power balance between the primary power demand and the secondary power demand is also obtained. A system power capability is calculated based on the desired power balance and the estimated power capability. The method of the present invention then determines if the driver power command exceeds the system power capability. If the driver power command exceeds the system power capability, the driver power command limited and thereafter the limited driver power command is executed.