In his 2016 memoir “Hillbilly Elegy,” JD Vance described a community in crisis.

The steel mill where his grandfather worked for nearly 40 years had been neglected and had endured layoffs in the 1980s, turning his hometown of Middletown, Ohio, into “little more than a relic of American industrial glory.”

“There is a lack of agency here,” Mr. Vance wrote. “A feeling that you have little control over your life and a willingness to blame everyone but yourself.”

On Friday, Mr. Vance returned to his roots with promises of a better future, and plenty of blame to go around.

Surrounded by union workers in the factory where his “Papaw” once welded steel, Mr. Vance said politicians of both parties had for decades embraced pro-immigrant and free trade policies that redirected jobs away from places like Middletown. He said the Democratic Party no longer resembled the one his grandfather once supported.

And with an eye on the November midterm elections and his political future, Mr. Vance drew on his Rust Belt roots to persuade voters that President Trump’s tariff and immigration policies would protect factory jobs and revitalize struggling towns.

“The future of our homes and communities is going to be built right here in Middletown,” Mr. Vance said. “My Papaw hated the politicians who ignored this place. He hated the people who saw this as the place of the past. He hated the people who forgot about this town when they should have been fighting for this town.”

For much of his political career, Mr. Vance has used his past in Middletown as a way to try to explain the grievances of the white working class, even as he transformed from a Never Trumper into Mr. Trump’s second-in-command. Now, Mr. Vance is turning to his origin story again as he ramps up travel ahead of the midterm elections that will in large part shape the final two years of Mr. Trump’s second term.

“Who do these Democrats put first? Everyone else,” said Mr. Vance, who was joined by Senator Jon Husted, Republican of Ohio. Mr. Husted is trying to hold onto his seat in a race against Sherrod Brown, a former senator from the state.

“You know who the Trump administration puts first?” Mr. Vance asked. “Americans.”

Mr. Trump also campaigned on resurrecting the U.S. manufacturing industry, although his on-again, off-again tariff policies have contributed to rising consumer prices. As Mr. Vance promised to invest in the future of the steel workers in Ohio, Mr. Trump and his aides considered a proposal to reduce tariffs on some Canadian steel from 50 percent to 25 percent, prompting pushback from U.S. steel mills.

And while Mr. Vance blamed immigration for threatening American jobs in the heartland, Ohio’s Republican governor has called the Trump administration’s plans to deport Haitians in the state a “mistake,” arguing that the move would hurt the local economy.

Mr. Vance on Friday tried to build support for the Trump administration’s approach to manufacturing, describing a $500 million injection of federal funds for the Cleveland-Cliffs factory, which went by another name when his grandfather worked there years ago.

That grant was actually first offered by the Biden administration to transform the steel mill into a more environmentally friendly factory. The plan — and the expected job growth from the investment — was celebrated by the local union at the time.

Under Mr. Trump, who has called such investments by the previous administration a scam, the money will be used to upgrade the factory’s coal-fired furnace. The Energy Department also said it would equip the factory with artificial intelligence to improve energy efficiency. But the department did not respond to questions about whether the investment would produce permanent jobs.

Donna Ballinger, a 62-year-old resident of Middletown and climate activist who lives 800 feet from the facility, said she was frustrated to hear of the pivot away from clean energy. She said she often wakes up to find a silver powder on her car, and is afraid to let her grandchildren play outside, given the polluted air.

“We are bombarded everyday by fallout, by noise, by toxic emissions,” said Ms. Ballinger, who stood outside Mr. Vance’s speech on Friday holding a sign saying: “we deserve clean steal.”

In his speech, Mr. Vance dismissed complaints by environmental activists as those of the “far left,” arguing that the federal funds would improve the factory’s technology to “optimize furnace operation and improve Middletown’s air quality.”

Lourenco Goncalves, Cliffs’ chief executive, said the investment would preserve roughly 2,300 jobs.

Whether Mr. Vance is correct about the Trump administration’s investment improving the quality of life in Middletown will not just be key for local residents and Republican prospects in November, but also his own political future. Widely considered a potential heir of the MAGA movement, Mr. Vance and his origin story will only be scrutinized more if he seeks higher office.

“I’m not saying it’s going to be easy or it’s all going to happen overnight,” the vice president said. “But in just 18 months, we have seen an explosion of rebuilding in the American heartland.”