AUGUSTA (AP) — About $1 million has been raised since June alone by supporters among the five Maine initiatives on the ballot this fall.

Voters will decide ballot questions in November on marijuana legalization; a tax to support public schools; universal background checks for gun sales; a gradual minimum wage hike; and ranked-choice voting.

The biggest contributors since June include author and activist Stephen King; the nation’s largest teacher’s union; a Washington state venture capitalist; and “dark money” nonprofit groups.

Aside from King, individuals in Maine contributed just shy of $38,000 of the $1 million.

It’s an unsurprising development in a campaign finance landscape marked by landmark court decisions striking down limits on unions, corporations, individuals and nonprofit groups’ contributions to political action committees, said University of New England political professor Brian Duff.

In Maine, registered political groups have raised $11.7 million so far this year — more than three times as much raised by this time in 2008 and more than double the amount raised at this point in 2012.

“It takes a while for people to gear up, to learn to identity donors who are most likely to be interested in state measures like this,” Duff said.

The National Education Association gave $300,000 to Citizens Who Support Maine’s Public Schools. The Augusta-based group is leading efforts to create a new fund for public schools by instituting a 3 percent tax on residents’ taxable income above $200,000.

The union also contributed $131,000 to the Mainers for Fair Wages campaign, launched by the Maine People’s Alliance and the Maine AFL-CIO. The hike would gradually increase the state’s $7.50 minimum wage up to $12 by 2020, then switch to annual cost-of-living increases.

Among out-of-state nonprofits, The Fairness Project, Fair Vote and Action Now Initiative donated about $140,000 to Maine groups working to pass the incremental minimum wage hike and ranked-choice voting that allows people to rank candidates.

The voting question follows criticism of Republican Gov. Paul LePage’s win without majority support.

Mainers for Responsible Gun Ownership, a group largely funded by a nonprofit backed by former New York City Mayor Michael Bloomberg, received a $125,000 contribution from Washington state entrepreneur Nicolas Hanauer and $25,000 from King, of Bangor.

In an email, King said background checks would ensure that private gun buyers don’t have records of violent crimes or outstanding restraining orders from spouses or children.

Hanauer, who’s donated more than $200,000 to ballot measures nationally since the mid-2000s, wasn’t available for comment. His colleague Zach Silk said Hanaeur only invests “in places where on-the-ground grassroots support is strong.”

The National Rifle Association’s advocacy fund and a smaller opposition group in Maine brought in about $12,000.

About $200,000 has been raised by the Campaign to Regulate Marijuana Like Alcohol, which supports the question to legalize the possession and use of marijuana by people at least 21 years old. It also would allow regulation of the sale, cultivation, manufacture, testing and distribution of marijuana.

Most of its contributions come from travel guru Rick Steves of Washington state and the pro-marijuana reform New Approach PAC, based in Washington, D.C. Steves didn’t respond to request for comment.