Supporters have billed the initiative as a way to strike a blow against the Supreme Court’s 2010 Citizens United ruling.

With 87% of votes counted as of Wednesday morning, Montana Constitutional Initiative 194 has received support from more than 65% of voters, with just 35% registering opposition.

The initiative prohibits what it describes as “artificial persons” — which includes corporations, nonprofits, trusts, partnerships, and trade associations — from giving money to political campaigns.

Supporters of the initiative have billed it as a way to strike a blow against the Supreme Court’s 2010 ruling in Citizens United v. Federal Election Commission, which opened the door to unlimited campaign spending in US politics.