Mainers 21 and older would be allowed to possess up to an ounce of marijuana and grow their own plants, and pot sales would be subject to a 10 percent tax under a proposal by a national group advocating for legalized recreational use in the state.

The Marijuana Policy Project, which led the successful drive to legalize recreational marijuana use in Colorado, will unveil its plan Tuesday. It is the second one to be released in the state this year and sets the stage for dueling campaigns pushing for legalization referendums in 2016.

“This is going to be an economic driver for the state. It’s the shot in the arm that Maine needs,” said David Boyer, Maine political director for the Marijuana Policy Project. “But we want to ease into this new market. We think it’s best to have a slow, responsible rollout to this new industry. Voters don’t want (marijuana) stores on every corner.”

In February, Legalize Maine submitted an application to the Secretary of State’s Office for a citizens initiative that also seeks to legalize and regulate marijuana. Legalize Maine touts its proposal as a “homegrown” plan that focuses on supporting cannabis agriculture and small-scale growers.

Scott Gagnon, director of Smart Approaches to Marijuana Maine, which opposes legalization, said his group continues to have concerns about access to marijuana and the normalization of the drug if either ballot initiative is approved.

“We think there is still a lot of concern across Maine and we hear it every day,” he said. “At the end of the day, we think Maine isn’t really ready to go down the road of legalization like Colorado.”

GATHERING SIGNATURES THIS YEAR

Legalize Maine expects to start gathering signatures in April and finish by the end of November, said the group’s president, Paul McCarrier. The secretary of state will issue a petition to circulate once the legislation is written and a fiscal statement is drafted by the state Office of Fiscal and Program Review.

To qualify for the ballot, each group must collect 61,123 valid signatures, or 10 percent of the total votes cast for governor last November. The filing deadline is Feb. 1, 2016.

Marijuana remains illegal under federal law, but Colorado and Washington state legalized the drug for recreational use in 2012. Last year, Oregon, Alaska and Washington, D.C., also approved measures to legalize recreational pot.

In addition to the efforts to get referendums on the 2016 ballot in Maine, Rep. Diane Russell, D-Portland, has submitted a legalization bill that the Legislature will consider this session.

TAXING SALES, CAPPING OUTLETS

Maine is among several New England states facing legislation and citizens initiatives that seek to legalize recreational marijuana. State legislatures in Vermont, Massachusetts, Connecticut and Rhode Island are all considering bills that would regulate and tax marijuana in ways similar to alcohol. Lawmakers in New Hampshire will also consider decriminalizing marijuana possession.

The Marijuana Policy Project was behind efforts in Maine last year to legalize pot in South Portland, Lewiston and York. South Portland voters approved the plan, Lewiston voters rejected it and York town officials successfully blocked the referendum from going to voters.

Under the referendum proposal from the Marijuana Policy Project, adults 21 and older would be allowed to possess up to 1 ounce of marijuana and grow six marijuana plants in a secure area of their home or yard. Marijuana sales would be subject to a 10 percent tax on top of the state sales tax. The first $30 million in tax revenue would be used for school construction, and revenue beyond that amount would be directed to the state’s General Fund.

The proposed legislation gives authority to the Department of Administrative and Financial Services’ Bureau of Alcoholic Beverages and Lottery Operations to license and regulate retail marijuana stores and cultivation businesses of various sizes. It also allows the state to cap the number of marijuana cultivator licenses until 2022 “to help ensure that the supply and demand for marijuana remain in relative stasis,” according to the proposal. There also would be a cap, which has yet to be determined, on the number of retail marijuana store licenses issued before 2019.

Boyer said his group’s proposal emphasizes local control and has provisions that allow towns to prohibit retail stores and commercial cultivation. Retail stores could allow customers to consume marijuana on the premises only if approved by the municipality.

“Our initiative takes marijuana out of the hands of criminals and drug dealers and puts it in the hands of state-licensed and regulated business owners who check IDs,” Boyer said. “Instead of having no control over marijuana, we will have control over who is buying it and who is selling it.”

The Marijuana Policy Project’s application for the petition includes the names of five registered Maine voters: Russell, the Portland representative; Aaron Libby of Waterboro, a former two-term Republican state representative; Matt Roy, a Lewiston School Board member and Androscoggin County commissioner; Rev. Deane Perkins of Belfast; and Sherry DaBiere, a Realtor from York.

PLAYING THE OUT-OF-STATE CARD

McCarrier of Legalize Maine, sponsor of the competing referendum, believes his group’s plan is a better fit for Maine because its policy is not driven by an out-of-state group. Legalize Maine’s plan puts more emphasis on local agriculture.

McCarrier also believes the Marijuana Policy Project will have trouble collecting enough signatures to qualify for the ballot if the Legislature approves a pending bill that makes it more difficult for groups to use out-of-state residents to gather signatures to advance ballot initiatives. That bill has been unanimously endorsed by the Veterans and Legal Affairs Committee.

Boyer, though, said that even if the bill is approved, “it will not be an obstacle.”