Advocates say the public needs to know the farm's name and its distribution network to protect their families.
A salmonella outbreak tied to cantaloupe has sickened about 140 people in 20 states and killed at least two Kentucky residents.
Food and Drug Administration spokeswoman Shelly Burgess says agency officials are still trying to determine the source of the salmonella, and they're withholding the farm's name to avoid releasing false or premature information.
Seattle lawyer Bill Marler has represented victims of foodborne illness for about 20 years. He says questions have arisen in nearly every foodborne illness outbreak about whether suspected contamination sources should be identified.