As voters consider marijuana-legalization efforts in several states this November, they can expect opposition from the usual pot opponents like law-enforcement groups and anti-drug activists – but some of the most ardent foes come, unexpectedly, from within the marijuana community itself.

Opponents include some in the medical-marijuana industry, concerned about what a wide-open recreational market would mean for their businesses. Advocates for recreational marijuana also fear the latest legalization measures come with so many restrictions that pot smokers might be better off, for now, within the existing medical-marijuana system. 

All five states considering legalization this November – Arizona, California, Maine, Massachusetts and Nevada – already allow the medical use of pot.

Perhaps the biggest battlefield is California, where voters will consider Prop 64, funded by Napster founder Sean Parker.

“I’m on the record totally opposing this law [California Proposition 64] that does not legalize marijuana,” said Steve Kubby, an original proponent of the 1996 ballot measure that legalized medical marijuana.

Prop 64 would technically legalize pot, but also impose a 15-percent tax on marijuana sales and empower a new bureau to enforce the regulations and issue licenses. The measure creates what supporters call a “seed-to-sale” system of tracking and regulating marijuana.

Kubby, who backed an alternate legalization measure that never made it to this year’s ballot, complained the Prop 64 proposal creates tougher punishments for people who have more than an ounce.

California’s marijuana industry is centered in Humboldt County, the redwood-forested coastal region 200 miles north of San Francisco. Yet a July 12 report in the Humboldt Independent found deep divisions within the California Growers Association, a cannabis growers’ trade group, over the “Adult Use of Marijuana Act.” An opinion poll found its members evenly split over Prop 64.

Some growers told the newspaper they feared the initiative would allow big marijuana companies to dominate the entire supply chain. The group reportedly had threatened to oppose the proposition until drafters included temporary limits on cultivation size.

Dale Gieringer says his group, California NORML, backs the initiative “but we definitely have reservations.” Medical patients are right to be concerned, he said, because it raises taxes on medical dispensary purchases and gives local governments the right to ban them. On the plus side, it reduces felonies.

Diane Goldstein, executive board member for Law Enforcement Against Prohibition (LEAP), touted the proposal. “This initiative is the best chance California has to end a failed war on marijuana resulting in the criminalization of almost half a million people in the last decade,” she said.

Such wide differences of opinion from within pro-marijuana circles are playing out in other states, also. The Massachusetts measure gives existing medical dispensaries preferential licensing treatment, so a number of existing companies have actively supported the measure.

But Dan Delaney, a Boston lobbyist who has helped medical-marijuana clinics seek licenses and is chairman of Safe Cannabis Massachusetts, opposes the measure. He is particularly opposed to language that limits the ability of local governments to regulate it and said many of the state’s hardcore pro-marijuana activists have joined with the anti-marijuana activists to oppose the measure. They view it as being “crafted by industry folks.”

There’s another potential foe that marijuana-legalization supporters might not have expected: the alcohol industry. US News reported in May that an alcohol trade group is funding opposition to the recreational marijuana initiative in Arizona, but that alcohol companies are backing a similar legalization measure in Nevada. A likely reason: The Nevada proposal gives alcohol distributors first crack at the distribution licenses.

The latest polls show legalization ahead in California and split in Massachusetts and Nevada. It’s behind in Arizona, but was ahead in Maine in May.

Steven Greenhut is a Sacramento-based journalist.