If enacted, the Arizona initiative would permit residents to possess 2.5 ounces of marijuana and grow 12 plants.
Residents in the nation's capital also may get a chance to vote on legalization in November.
D.C. Cannabis Campaign leaders plan to submit draft ballot language Friday with the city's elections board. The proposal would legalize possession of 2 ounces and six plants by adults over 21.
The board will deny the proposal if it decides it involves appropriation of city funds – a determination that's doomed other initiatives – but campaign coordinator Adam Eidinger tells U.S. News lawyers advising the effort are confident officials will approve the "bare-bones" and loophole-ridden proposal because it avoids enforcement matters.
The activists filed a decriminalization ballot measure as a trial balloon last year and used the board's rejection as a roadmap for writing the legalization proposal.
If the draft language is rejected, activists may sue. If it's approved, the campaigners plan to begin petition-gathering in late February or early March, with a goal of netting the required signatures by the end of June.
"People have a lot of anger about this and they're tired of bailing people out of jail," Eidinger says.
Although an April PPP survey put support for legalization at 63 percent in D.C., Eidinger says supporters "can't count out the opposition" and estimates a half-million dollar campaign is necessary to win.
"I think we're going to lose support once opposition comes out," he says.
The campaign leader notes the ballot language will cap the number of plants per residence at 12 to head off fears about fraternity houses with 100 plants.
Councilman David Grosso, an independent, introduced a legalization bill in the 13-member city council in September. It's unlikely to pass in the near future, but a decriminalization bill sponsored by Tommy Wells, a Democratic councilman running for mayor, appears certain to prevail this year.
"There's going to be an increase in demand with decriminalization, but there isn't going to be anywhere safe for people to go purchase marijuana," Grosso told U.S. News after unveiling his bill. "They're still going to be on the street corners, we're still going to have problems with violence on the street, with people getting arrested for nonviolent offenses."
Eidinger says if the referendum is approved by voters in November, it would be up to the city council to embrace the spirit of the initiative and pass the reform into law. Congress has the power to block legislation in D.C. and did so for years after city voters approved medical marijuana in 1998. The city's first medical marijuana facilities opened in July 2013.
In addition to voter-driven initiatives, legalization bills have been proposed in at least 13 state legislatures.
"Rhode Island would be the most likely if a legislature passed [legalization] this year," says Tvert, who co-directed the successful Colorado initiative campaign. "Last year there was a bill to regulate and tax marijuana like alcohol that received significant bipartisan support."
Vermont's governor, Democrat Peter Shumlin, said he's closely watching developments in Colorado and Washington, but that he doesn't consider legalization a priority in 2014.
New Hampshire's legislature will consider a legalization proposal Jan. 15, state Rep. Steve Vaillancourt, a Republican, tells U.S. News. Its prospects are unclear.
Although it's possible several states will legalize marijuana in 2014, the MPP sees 2016 as a more likely watershed year for legalization and plans to support voter initiatives in Arizona, California, Maine, Massachusetts, Montana and Nevada.
The Department of Justice announced Aug. 29 it will not seek to block the opening of recreational marijuana stores, as long as there's tight state regulation. Marijuana remains illegal under federal law, but officials cite a lack of manpower to force prohibition upon states where marijuana is legal.