PITTSBURGH (TNS) — When President Joe Biden’s energy secretary visited the Cleveland-Cliffs Butler Works steel plant earlier this year, the company painted the floors and hung large banners celebrating the president for “Investing in America.”

Dozens of workers in yellow hard hats offered their applause for an amended energy policy that spared jobs at the factory 30 miles north of Pittsburgh. But many others stayed home in protest, unwilling to give Mr. Biden credit when it was his administration’s proposed policy that threatened their jobs in the first place.

As the president and his potential successor, Democratic presidential nominee Vice President Kamala Harris, visit the Pittsburgh region this Labor Day, experts and labor leaders say they’re courting a complicated union vote that could decide the 2024 election.

“I would expect union leadership to continue to stick with the Democrats,” said David N. Taylor, president and CEO of the Pennsylvania Manufacturers’ Association, “but from the battles that I’ve seen, at least in Harrisburg, more and more there’s a conflict between the radical greens and the hard hat jobs for working people.”

“When the Democrat agenda is dominated by the environmentalists and their concerns, people who work in industry see that as being necessarily an attack on their jobs,” he said.

On the Republican side, workers see a candidate who backs production, Mr. Taylor said. “I would expect that former president Trump would be able to gain a lot of supporters. … When on the other side, you have people who don’t want shovel to touch dirt.”

If elected, Ms. Harris would likely inherit the Democratic party’s fundamental challenge of protecting jobs while accelerating climate policy, with decisions landing as hard in Pennsylvania as any part of the country. Her roundabout on fracking — she no longer supports a federal ban on the practice — has become a frequent criticism.

Meanwhile, Mr. Trump’s more consistent message of “Jobs! Jobs! Jobs!” appears to be resonating.

“Probably 90% of the employees here at Cliffs in Butler are voting for Trump,” said Ed Weber, 45, a steelworker who’s been at the plant for more than a decade.

That support comes “despite the United Auto Workers endorsing Harris,” he said.

As for whether the visits from Ms. Harris and Mr. Biden change anything, another Butler worker, Robbie James, 31, said most union workers will back “the candidate that won’t shut down their jobs.”

Mr. Trump made his own visit to the state last week, telling a packed audience in Johnstown that “we will no longer allow foreign countries to take our jobs.”

Because of Pennsylvania’s significance to the election, voters here have come to expect visits from presidential hopefuls, said Jeff Brauer, political science professor at Keystone College in northeastern Pa.

“And candidates who don’t show up can end up paying a price,” he said, recalling Hillary Clinton’s narrow defeat in Michigan in 2016 after she spent little time in the state.

The visits can also offer the opportunity to win over the union rank and file, not just leadership, Mr. Brauer said.

“Candidates love to get and tout endorsements. But endorsements don’t always translate into votes. In this case, individual union members will make up their own minds based on their personal perspectives.”

Even if local workers’ minds are fixed, spending the holiday in Pittsburgh could send a larger message across the country, said Christopher Borick, political science professor at Muhlenberg College in Allentown.

“Harris and her team know that a visit won’t shift the vast majority of union workers who are supporting Trump,” he said. “But it may help energize union members and leadership that support her candidacy and boost their outreach efforts over the next few months.

“A visit to a location like Pittsburgh that is steeped in labor history is aimed at an audience that goes well beyond southwestern Pennsylvania,” he said.

Mr. Taylor, the Manufacturers’ Association leader, described that campaign as an uphill battle.

“Four years ago, Joe Biden was plausible,” he said. “Having a California liberal as the nominee instead of the guy from Scranton, I think it’s going to make the union leaders’ job harder to try to keep their rank and file in line.”