Federal Resources Minister Madeleine King says workers threatening strike action at the nation's biggest port deserve "every single cent" of what they earn while a peak industry body says they are "letting down everyone".

BHP could lose $100 million in revenue a day if two unions vote for work stoppages, unless it can find about 450 replacement staff in Western Australia.

Unionised workers at BHPs operations in Port Hedland could walk off the job as soon as next week after endorsing protected industrial action.