The Center for Biological Diversity is asking the U.S. Fish and Wildlife Service to set aside more acreage than the agency originally said was necessary for jaguar reintroduction in the southwestern states.
But representatives of livestock owners say they oppose an expansion.
The federal government agreed to set aside 1,300 square miles in August, but the center says the locations are not ideal and amount of acreage is not enough for the big cat's reintroduction.
The Center is asking for more land in Pima, Cochise and Santa Cruz counties in Arizona, and Hidalgo County in southwestern New Mexico, saying the new request more closely fits the jaguar's natural habitat in Brazil.
Organizations representing livestock owners oppose the additional acreage request, saying it would increase the burden they already face with the Mexican grey wolf reintroduction program.
The U.S. Fish and Wildlife Service is working on an economic analysis of the proposal, and is seeking public comment.