Lobbying lawmakers for a rate hike is one thing, but now Montana’s biggest electric and gas utility is battling to block a referendum on expanding gun rights.

Publicly regulated NorthWestern Energy contends the measure would make it harder to keep their workplaces weapons-free. But the Montana Shooting Sports Association accuses the utility of sticking its nose into a political debate where it doesn’t belong.

“NorthWestern is opposing a bill that has nothing to do with their corporate mission delivering electricity to its customers,” the group’s Gary Marbut told FoxNews.com Monday.

“Because they are a large corporation and have been given a monopoly by the Public Service Commission, they really have no business weighing in on civil rights.”

- Gary Marbut, Montana Shooting Sports Association

He claimed NorthWestern’s opposition was contrary to the interests of its 542,000 gas and electric customers in Montana, most of whom are avid gun owners and hunters.

“Because they are a large corporation and have been given a monopoly by the Public Service Commission, they really have no business weighing in on civil rights,” Marbut said.

Marbut also accused NorthWestern of misrepresenting the impact of the bill on the utility. He said it would only apply to government entities on the state and local level, not private businesses like the utility.

The bill’s sponsor is Matthew Monforton, a Republican from Bozeman, who consulted with Marbut on the bill. On Friday he amended the bill to clarify that only government entities could be sued for infringing on a gun owner’s rights to bear arms.

With the new language the bill then passed the House Judiciary Committee on a 12-9 party-line vote with the Republicans in the majority.

Monforton told FoxNews.com the measure is now headed to the full House for a vote later this week or early next week. He predicted the vote could be close because of the controversy surrounding the bill. If it passes, the bill would go to the Senate. With legislative approval it would be on the 2016 Election Day ballot. The bill does not need the approval of Gov. Steve Bullock, a Democat, to get on the ballot.

Monforton said he drafted the bill as a preemptive strike.

“What we were concerned about is further action on gun control by (former New York Mayor Michael) Bloomberg and other liberal anti-gun advocates,” Monforton said. “It buttresses Montana’s constitutional right to bear arms and offsets efforts to turn Montana into a gun control state.”

Two weeks ago NorthWestern’s chief lobbyist John Fitzpatrick told the Judiciary Committee the bill would not prevent lawsuits against the utility or schools that forbid guns.

“You can talk all you want about the state establishing a compelling right to take away gun rights, and that’s going to fail miserably, in the context of someone saying, ‘All this bill does is allow kids to bring guns to school,’” Fitzpatrick testified.

He was joined in opposition by a gun control group funded by Bloomberg.

Reached Monday in his Helena office, Fitzpatrick referred FoxNews.com to a utility spokesman who declined comment on the bill.

In a March 14 blog posting on its website, the utility explained its opposition.

“This is a bill that we feel limits, or creates a pathway that could limit, our ability as an employer to implement policies that are consistent with our safety values,” NorthWestern said.

The post also countered accusations that ratepayers were picking up the tab for utility’s lobbying expenses and that the company had financial ties to Bloomberg.

The utility said its lobbying expenses are borne by shareholders, and that to its knowledge “Michael Bloomberg does not have financial interest in the company.”

During the back and forth between NorthWestern and Marbut over the bill, the utility accused the gun advocate of threatening the utility.

“Dang, I didn’t know I was so powerful that a giant corporation would feel ‘threatened’ just because I might attend a public hearing, and might even use my First Amendment right to speak,” Marbut said in March 22 letter on his website.