For the past 38 years, Randy Tocci, 58, has worked at the Imerys talc plant in his hometown of Three Forks, Montana, a quiet community of 2,000 residents just a few miles from where the Madison, Gallatin, and Jefferson rivers converge to form the Missouri. As lead maintenance warehouseman and president of International Brotherhood of Boilermakers Local #D239, Tocci considers himself a lifer at the company.

Yet, despite increasing profits, the French-owned corporation recently banned all union workers from the job site and posted a security detail at the company gates. The lockout began on August 2, six days after Imerys announced revenue of $2.6 billion (an 11.9 percent increase) in the first half of 2018 and the same day union members voted 28-7 to reject a contract that would have reduced overtime pay, frozen pensions, and eliminated health insurance for new retirees.

Tocci (pronounced toss-ee) and his colleagues were livid. “When you’re helping make the company millions of dollars,” he told me, “there’s no reason for them to take away benefits that have been in place for decades.”

Since then, Imerys’s actions have made headlines across Montana, and elected officials from both parties have urged the company to continue negotiations. But the strongest words of condemnation have come from Senator Jon Tester, a grain farmer and second-term Democrat who’s facing a tough reelection bid.

On Labor Day, he delivered a fiery speech from the back of a pick-up truck to a large crowd gathered at the picket line. “We’re tired of this crap!” he shouted, planting one cowboy boot on the wheel hub and pointing toward the mill. “It’s time to get pissed off, to stand up for these workers, and make ’em open those gates!”

It’s been 38 years since the last labor lockout in Montana, a state that went for Trump by more than 20 points and where the once-powerful labor movement has long been in decline. Nevertheless, a 35-worker local is suddenly winning bipartisan support, and their fight against a $4.2 billion corporation has become a flashpoint in a close election that could determine control of the US Senate.

Built in 1959, the Imerys talc plant looms large at the south end of Three Forks. The steaming complex of white storage tanks and tall warehouses are visible from the cafes, motels, and tackle shops downtown. In 15 minutes, a worker can walk from the saddle outfitter on Main Street, past the company-sponsored baseball diamond, across the railroad tracks, and into the mill yard.

Since August 3, however, approximately 50 non-union replacement employees have been driven to the mill from their out-of-town hotels on the company dime. The unlabeled vans with blackout windows zip by picket lines that are staffed by locked-out workers 24 hours a day. On September 20, the boilermakers’ camp at the main gate was supplied with a tarp shelter, a few lawn chairs, and some homemade signs. It seemed like a lonely place to spend the night.

By daybreak, 10 to 15 supporters organized by the state AFL-CIO, located in nearby Helena, had joined about 28 workers for a rally timed to coincide with the 7 am shift change. They held signs with hand-written messages: “Whose side are you on?” “Put us back to work!”

When a white company-owned pickup truck crossed the tracks and headed for the gate, everyone lifted their signs and converged, slowing the vehicle to a crawl. The boilermakers raised their voices. “Turn around, man, turn around!” “Don’t be an asshole!”

After 49 days on the line, hard feelings were obviously growing among locked-out workers. Gene Townsend, 68, a former union member and seven-term mayor of Three Forks, said their frustrations are justified. “From what I can tell, the company is refusing do anything to try to get to an agreement,” he told me. “It’s going to be their way or nothing at all.”

The union started working toward agreement with Imerys following the expiration of an eight-year contract in May. The previous contract was signed in 2010 with the former owner, Brazilian mining conglomerate Rio Tinto. Imerys purchased the operation in 2011, and, this spring, the company had their first opportunity to negotiate a new contract. They wasted no time proposing several changes.

In a statement delivered via FTI Consulting, a New York crisis-management firm, Imerys explained that seniority provisions were of particular concern to the company. “Our top priority is always keeping our employees safe,” the statement reads, “which is why we believe that ability and qualification to perform a role—rather than seniority—must be the primary factor in selection” for jobs at the mill.

Union members have countered that changes in seniority provisions are an effort to diminish the influence of long-term employees. They also argue that losses in health insurance and pension benefits are unacceptable. Over the course of three months, union members voted to reject the offer three times, but each time Imerys refused to make adjustments. After the third vote, Imerys escorted union workers off the property, and communication between the negotiating parties broke down.

The lockout immediately drew headlines, and Montana elected officials and candidates began lining up behind the workers. In August and September, Democrats Governor Steve Bullock, Senator Jon Tester, and US House candidate Kathleen Williams all visited the picket line. Republicans Senator Steve Daines, Representative Greg Gianforte, and Attorney General Tim Fox offered statements of support online. All urged the company to continue negotiations.

While Imerys has responded to this unusual display of bipartisan concern by holding additional negotiations with the union, they have also refused to change their offer, and this approach is fueling resentment in Three Forks, where “Hey Imerys! End the Lockout!” yard signs have popped up in front yards across town.

“I feel the sentiment within the community is with the local guys,” Townsend said, “and I feel there’s a lot of animosity toward the company.” Whether this animosity is enough to change the company’s position is an open question. But, as the lockout drags on and the election draws closer, a new question has emerged: Will this labor dispute have national repercussions?

On October 3, Senator Tester introduced the Prohibiting Incentives for Corporations that Kickout Employees Tax (PICKET) Act, which would eliminate tax breaks for corporations that lock out workers during a labor dispute. “When corporations sell their workers downstream,” he said, “they shouldn’t be able to turn around and cash in on the backs of taxpayers.”

Then, on October 23, Tester’s campaign posted a video on Facebook advertising an endorsement from the AFL-CIO. The video, which includes affirmations from three different union members, leads with a statement from Tocci: “I support Jon for his reelection campaign, and I’m proud to do it.”

Meanwhile, State Auditor Matt Rosendale, the Republican challenger for US Senate, has kept his distance. In late August, he joined other Republican officials, saying, “Imerys should do the right thing and meet with the boilermakers.” Since then, he’s been silent, and repeated requests for comment on this story, both to his state office and his campaign, were not returned.

Several invitations to meet with the union have similarly been ignored, even though Rosendale has recently been in the neighborhood. On October 14, when Tester made a second visit to the picket line, Rosendale stopped in Three Forks to visit with voters but avoided the picket line.

For Tocci, the contrast between those two campaign stops was glaring. “To me, it shows who really cares about the working people of this state,” he said. “Neither Matt Rosendale nor Greg Gianforte have set foot on the line and shown support for us. To me, it looks like they’re backing the multimillionaires and not the working people of Montana.”

Tester and Williams have both deployed a similar line of criticism against their wealthy opponents. Rosendale, a former Maryland real-estate developer, reports assets up to $32 million. Gianforte, a founder of RightNow Technologies, is the richest man in Congress with estimated assets of $315 million. More importantly, both men are running campaigns focused on supporting President Trump, an alleged billionaire, while Tester and Williams claim Trump’s tariffs and tax cuts hurt the middle class.

It’s unclear whether this is a winning strategy, but political scientists seem to agree that the Imerys lockout underlines the differences between the candidates. “This issue won’t make or break a campaign,” said David Parker, a political-science professor at Montana State University, “though it does feed into a larger narrative that Tester’s campaign is telling, which is he’s the guy who looks after the little guy, and this is a piece of the populism pie that Rosendale isn’t talking about.”

Jeremy Johnson, a political-science professor at Carroll College, in Helena, agrees on the second point. “I think this lockout is an issue that fits with Tester’s brand,” he says, “especially as Rosendale has attached his campaign to Trump and ceded more local issues like this to Democrats.”

Johnson said that the lockout might be consequential in a close race, particularly because Three Forks is located in the fastest-growing and third-most-populous county in Montana. “Gallatin County used to be red and now has turned blue, so it’s pivotal,” he said. “Tester got 52 percent of the county vote in 2012, and he certainly wants to build on that in 2018.”

In many states, a tight vote in a single county might not be significant, but close elections are common in Montana. Tester won by 3,500 votes in 2006 and 18,000 votes in 2012, and he’s never secured more than 50 percent of all ballots cast.

To complicate matters further, Montana is a fiercely independent state that frequently confounds pollsters. In 2016, Trump won by 20 points, but a Democratic governor was also reelected. This year, analysts are again struggling to predict outcomes. The Cook Political Report classifies the Senate race as a “toss-up” and the House race as “competitive.”

Tocci was well aware of the bigger political picture on October 18, as he walked the picket line, trying to keep warm before the onset of winter. It had been 77 days since the lockout began and would be 18 more before the presidential election, but his primary focus was on family. He and his wife have six children and are currently depleting their savings to make mortgage and insurance payments.

“It’s a struggle,” he told me. “It’s not where I want to be. I want to be in the plant working, but the company is hell-bent on breaking the union, and forcing us to accept a shitty contract.”

He didn’t hesitate when asked whether the union would indeed be broken: “Not if I have anything to do with it.”

UPDATE: During negotiations on October 30, Imerys conceded to several worker demands, and the union voted to accept the deal, ending a 90-day lockout. Union members will return to the talc plant on November 5 under a new three-year contract that protects seniority as a factor in job selection, retains overtime pay, and extends health benefits for new retirees through 2019. “Thirty-five individuals stood up to a multibillion dollar corporation,” Randy Tocci said, after the deal was approved. “We helped drive this message across the country—we shouldn’t let these huge corporations that are making millions and billions bully us and take away our benefits.”