Environmentalists say it will protect critically endangered California condors. Gun rights advocates worry it would create a virtual ban on hunting.
The use of lead in ammunition is already prohibited in the main California condor range between San Jose and Los Angeles.
The ban is supposed to help in the comeback of North America's largest land bird, which three decades ago, had declined to just 22. But lead is still the leading cause of death to the California Condor.
"The cost of treating lead poisoning and wildlife reach hundreds of thousands of dollars a year for both public and private entities here in California," said Jennifer Fearing of The Humane Society of the U.S.
A spirited debate awaits the Senate when it returns from summer break over whether the prohibition should be extended throughout the entire state.
Researchers found when farmers kill nuisance animals or hunters leave behind their prey, condors will ingest lead bullets and fragments while eating the carcasses and die.
"Scientific evidence is clear that there is no safe level of lead exposure to humans or wildlife," said Assembly Member Anthony Rendon (D-Lakewood).
But the gun industry and hunting groups oppose the ban and feel this is really a backdoor attempt to ban hunting altogether in California. They say it's very difficult to buy non-lead bullets anywhere.
"The fact that a product is advertised does not mean it's available," said Sam Paredes of Gun Owners of California. "If you go to a lot of the people that show non-lead ammunition being available, it's back-ordered and they cannot tell you when they're going to be able to deliver."
And less toxic alternatives like copper bullets are so expensive, they're unaffordable.
"That's why we view this right now as a ban on traditional hunting in California because we cannot get the non-lead ammo," said Kathy Lynch of the National Shooting Sports Foundation.
If the statewide ban goes through, California would be the first state in the nation to do so.