HELENA — The state attorney general’s office asked the Montana Supreme Court on Monday to maintain the state’s century-old prohibition on corporations making independent political expenditures until the U.S. Supreme Court reviews its recent decision.

Attorney General Steve Bullock and his staff were responding to a motion filed last week by Western Tradition Partnership Inc., asking the Montana court stay, or refrain from enforcing, the ban until the U.S. Supreme Court reviews the ruling.

Last month, the Montana Supreme Court, in a 5-2 decision, reinstated the state’s voter-passed 1912 ban, overturning a District Court ruling that struck it down.

Western Tradition Partnership, a political group based in Washington, D.C., now known as American Tradition Partnership, has said it will ask the U.S. Supreme Court to consider an appeal of the Montana Supreme Court decision.

The group said the Montana decision fails to follow the U.S. Supreme Court’s 2010 precedent, Citizens United v. Federal Election Commission. That decision prohibits governments from limiting independent spending for political purposes by corporations and unions.

The state attorney general’s office said Western Tradition Partnership’s request for a stay amounts to the group asking for an injunction.

“Such an injunction would disrupt nearly a century of campaign finance law in this state, unleashing the very evils this court held Montanans have a compelling interest in preventing, in the midst of a primary campaign already in full swing,” the attorney general’s staff said.

Maintaining the century-old status quo would have no practical impact on Western Tradition Partnership, the attorney general’s office said. And it would have no impact on the other two plaintiffs in the original lawsuit, Champion Painting Inc., of Bozeman, and Montana Shooting Sports Association Inc., of Missoula, the office said.

The three corporations have not yet filed a petition for certiorari with the U.S. Supreme Court, the attorney general’s office said. Such a petition couldn’t be resolved before Montana’s June 5 primary election at the soonest, because of filing deadlines, the attorney general’s office said.

“Any injunction would throw the primary campaign, at least, into chaos as the hundreds of Montana candidates and political committees (including corporations) that play by the existing rules, and voters themselves, suddenly face an onslaught of anonymous, unaccountable and corruption attacks by foreign corporations, such as ‘the shadowy backers of WTP,’ ... who would flout the law,” Bullock’s office said. It was referring to the Montana Supreme Court’s description of Western Tradition Partnership.

The Montana Supreme Court decision said corporations already can participate in state politics by forming political action committees and by hiring lobbyists to attempt to influence elected officials.

Last week, Margot Barg, a Bozeman attorney representing Western Tradition Partnership and the two corporations, sought the stay from the Montana Supreme Court.

“The corporations want to do what the U.S. Supreme Court said that Citizens United may do under the First Amendment, i.e., make independent expenditures from general corporate funds,” Barg said. “Under a stay, Montana would be barred from preventing this while the U.S. Supreme Court considers this case. But Montana has no strong interest in enforcing a likely unconstitutional ban.”

American Tradition Partnership is a conservative political group that describes itself as “a no-compromise grassroots organization dedicated to fighting the radical environmentalist agenda.”

It has filed two other lawsuits challenging Montana laws that limit political donations, require disclaimers to identify who is paying for political advertising and require the disclosure of who is spending money in political campaigns.