The campaigns fighting for and against a measure to make legal limited possession and retail sales of marijuana have collectively raised and spent more than $3 million so far this election season, according to an analysis of campaign-finance reports.

Fundraising by the Campaign to Regulate Marijuana Like Alcohol, which backs Amendment 64, dwarfs that of Smart Colorado, the main group opposed, by a nearly 4-1 margin. Both sides report receiving more financial support from outside the state than from inside it.

Taking into account other groups working for and against the measure, total campaign fundraising on the amendment this season is close to $3.7 million.

Through the middle of this month, the Campaign to Regulate Marijuana Like Alcohol had raised more than $1.3 million in monetary contributions. The campaign also benefited from another $39,000 in in-kind contributions and a $400,000 loan. The loan, as well as $830,000 in monetary contributions, came from the Washington, D.C.-based Marijuana Policy Project, a drug-reform organization that is active in marijuana-legalization and -liberalization efforts across the country.

The campaign’s biggest individual donor is San Francisco-based Internet entrepreneur Scott Banister, according to the reports, which show that Progressive Insurance chairman Peter Lewis and Dr. Bronner’s Magic Soaps have also written large donations.

The campaign has spent $1.6 million.

Meanwhile, Smart Colorado has reported raising $433,000 in monetary contributions. Its largest donor is the Florida-based organization Save Our Society From Drugs, which has given $210,000. The campaign has also received large donations from Visit Denver, Trice Jewelers, the Focus on the Family-connected group CitizenLink and Cherry Hills Village mining and steakhouse boss Steve Mooney.

Smart Colorado has reported spending $215,000.

Though the campaigns received more contributions, numerically, from inside Colorado than from outside it, both campaigns have gotten more money from out-of-state sources.

About 51 percent of Smart Colorado’s money comes from outside Colorado, according to a Denver Post analysis. Roughly 89 percent of the Campaign to Regulate Marijuana Like Alcohol’s money is from out of state.

Roger Sherman, Smart Colorado’s campaign director, criticized his opponents’ out-of-state support.

“They are hijacking our state’s Western heritage of direct citizen access to the ballot in an attempt to further their agenda and pushing it with Hollywood celebrities,” he said.

Mason Tvert, one of the leaders of the pro-Amendment 64 campaign, said the amendment — along with others in Washington state and Oregon — has spurred a nationwide discussion about marijuana policy, a scope that is reflected in the donations.

“Ultimately, the voters of Colorado are going to decide on this initiative,” he said.

John Ingold: 303-954-1068, jingold@denverpost.com or twitter.com/john_ingold