“That really was the beginning for me of understanding more about working class issues and how we get left behind,” Jackson told the Globe in Skowhegan.

After becoming a logger himself, he experienced firsthand what he believed were unfair actions by big conglomerates that wanted to use cheaper Canadian labor over Maine workers — and then ran for office out of outrage. Along the way, he joined five unions; he currently is a dues-paying member of three, the biggest national unions representing engineers, machinists, and painters.

The organized labor movement, and its fundamental vision of working class solidarity overcoming the abuses and predations of entrenched power and capital, is inseparable from Jackson’s own deeply held vision. At its core, it fits on a bumper sticker: “We are not from the left. We are not from the right. We’re from the bottom, and we are rising,” he has said.

On Jackson’s car, a venerable Dodge minivan he drives himself on the campaign trail, he doesn’t have a sticker for his own campaign — just one that says “SOLIDARITY.”

Without the labor movement, he likely also wouldn’t be in the campaign right now. When Platner dropped out of the race in July, Jackson’s labor allies organized so effectively and quickly on his behalf that the nominating convention a few weeks later became a fait accompli.

To hear them tell it, going all-in for Jackson was not even a thought: he had done the same for them.

“For him, it’s not a transactional relationship,” Francis Eanes, the executive director of the Maine Labor Climate Council, said at a Lewiston brewery where supporters sang karaoke to Dolly Parton’s “9 to 5.” “He’ll leave the campaign trail and come to our organizing events. He’ll be the first one on the picket line, even at 5 a.m., before the camera people show up.”

It’s a conspicuous moment for a campaign like Jackson’s. Nationally, the labor movement is finding fresh blood and new champions to reverse decades of decline. This midterm election, which will be defined by voters’ suffering over rising costs, offers an especially favorable environment for organized labor’s pitch.

And Democrats have been anxious to find candidates who can reconnect with the working class — in Maine, some had believed they had one in Platner.

Jackson’s performance against Senator Susan Collins, then, could become a signal of just how potent a playbook of labor-centered, working class politics is for Democrats in this era.

The significance of the race is so obvious to the national labor movement that one of its highest-profile leaders, AFL-CIO president Liz Shuler, traveled to Maine to spend Labor Day campaigning with Jackson.

“Troy Jackson winning would prove our theory of the case that people want people in office who speak their language, who can actually make a positive change on the issues that matter to everyday working people,” Shuler said on the eve of Labor Day in Orono, where the University of Maine graduate workers union gathered for a contra dance event to benefit Jackson.

Jackson’s diagnosis of Democrats’ recent woes with the working class is simple: “Overall, we quit talking about economics,” he said. He acknowledged that some voters fled the party in favor of the GOP over perceptions that Democrats had gone too far on social issues.

“I’m asked all the time about transgender people and stuff like that. I’m not going to demonize them. I’m not going to leave them behind,” said Jackson. “But we kind of quit talking about everyday working class issues, and that’s where the problem is.”

Before being term-limited out of his state Senate seat in far northern Maine, Jackson was winning a district that had long since broken for President Trump — something he attributes to his longstanding, consistent emphasis on economic issues.

“Some people don’t believe the Democratic Party is fighting for working class people,” he said. “I don’t agree with that.”

In front of crowds, he is a halting orator who does not go in depth about other issues of national import — though at several campaign Q-and-A appearances he didn’t leave until every guest asked a question.

But Jackson’s Labor Day weekend swing through the state, packed almost exclusively with labor-oriented events, was a timely opportunity to play to strengths. On Saturday, he held a town hall in Jay, the site of a high-profile 1980s strike by the United Paperworkers union at the Androscoggin Mill. Some attendees at Jackson’s event were personally impacted by the episode.

At a South Portland coffee shop on Sunday morning, Jackson met with nurses, whose cause — legislation to lower nurse-to-patient ratios in hospitals — he pushed as state Senate president.

Later, in Orono, Jackson spoke with members of UMaine’s graduate workers union, who credit his support in their nearly two-year battle with the university for a contract, which concluded successfully last year. “Now it’s our turn to show up for him,” said psychology doctorate student Aurora Green, the president of the union.

Many in the Maine union world shared similar stories about Jackson; over his long career in the state legislature, he was their most reliable ally.

“Troy was standing shoulder to shoulder with us well before the Senate or governor’s race,” said Amanda Gavin, a professor who was a leader of the drive to organize UMaine grad workers and faculty in 2022. “That’s what gives him street cred.”

An undercurrent to labor’s support for Jackson is the belief that his position can’t be taken for granted. Collins, who has won major labor endorsements before, has a friendlier record toward organized labor than most Republicans: she had a 44 percent score from the AFL-CIO last year, compared to a 4 percent average from her GOP colleagues. But Collins is not a supporter of some of labor’s key legislative priorities, like the PRO Act, a sweeping bill meant to strengthen protections for collective organizing and bargaining.

The labor world is hardly a monolith, however. Bath Iron Works shipyard workers have expressed support for Collins in this campaign, but the local union representing them has not endorsed. The national organization backs Jackson.

The Collins campaign did not return a request for comment.

Democrats don’t hold unanimous positions on labor, either — another reason why unions are enthusiastically mobilizing for Jackson. Governor Janet Mills, who many once expected would be the party’s nominee to take on Collins, clashed often with labor interests, as well as Jackson himself, during her two terms as governor.

Still, while Jackson focuses on Collins, Platner’s shadow remains hard to shake. Speaking to crowds, Jackson almost always acknowledges the unusual, and for some people painful, circumstances around his rise to the Senate nomination.

Amid roiling debates within the party about what it means to have authentically working class candidates, there is a sense among some Democrats that Jackson — though less polished and dynamic as a candidate than Platner — is the real deal.

What Platner perhaps was pitching himself as, said Gavin, “that is who Troy really is.”

“He is the working class champion,” she said, “we needed all along.”

Sam Brodey can be reached at sam.brodey@globe.com. Follow him @sambrodey.