The Pima County Board of Supervisors is backing a resolution opposing the planned open-pit copper mine southeast of Tucson.
Tuesday's 3-2 vote includes language directing County Administrator Chuck Huckelberry to take all necessary measures to protect the health, safety and welfare of southern Arizona residents when it comes to the possible development of the $1.9 billion project in the Santa Rita Mountains.
Supervisor Sharon Bronson says if all administrative appeals are exhausted, the county may choose to join other existing legal challenges to the mine.
The Tohono O'odham Nation, Pascua Yaqui Tribe and Hopi Tribe also are opposing the mine project along with at least four environmental groups.
They say the mine would bring harm to wildlife and protected lands and have detrimental impact on water and cultural resources.