SAN FRANCISCO —A long-anticipated campaign to legalize recreational marijuana use in the state that produces more pot than any other commenced in California on Wednesday as supporters announced they have collected enough signatures to put a voter initiative on the November ballot.

A well-funded and politically connected coalition spearheaded by former Facebook President Sean Parker said it has collected 600,000 signatures from registered voters – far more than the 365,000 needed – ahead of a July 5 deadline.

Stressing what promises to be a dominant message of the campaign, Lt. Gov. Gavin Newsom said the 62-page initiative will make it harder for people under 21 to obtain pot and easier for police to crack down on illicit sales than it has been in the two decades since California became the first U.S. state to legalize medical marijuana.

“You do not need to be pro-marijuana to be pro-legalization,” said Newson, the father of four young children who hopes to become governor in 2018. “We are not promoting something that is not already ubiquitous in the state of California.”

In Maine, residents also will be voting in November on legalizing recreational marijuana use statewide after a petition drive put the issue on the ballot. Voters in Portland and South Portland already have approved local referendum campaigns legalizing possession of small amounts, but the drug remains illegal under state and federal law.

The California measure, known as the Adult Use of Marijuana Act, would allow residents and visitors 21 and over to buy an ounce of marijuana and marijuana-infused products at licensed retail outlets and also grow up to six pot plants for personal recreational use.

Smoking weed would remain off-limits in places where tobacco use already is prohibited, including restaurants, bars and other enclosed public places.

Sales of both recreational pot and medical marijuana initially would be subject to a 15 percent excise tax. Cities and counties would retain the right to prohibit marijuana-related businesses and to impose their own fees and taxes. State officials estimate the measure could net as much as $1 billion a year in new tax revenue for state and local governments.