Less than 30 miles south of the Fiserv Forum, the Wisconsin convention center where Republicans confirmed Donald Trump as their nominee for president for the third time, lies the site of a project Trump predicted would become “the Eighth Wonder of the World”.

While still in office, the then president traveled to Mount Pleasant in Racine county to break ground on a sprawling facility that the electronics manufacturing giant Foxconn had agreed to build – in exchange for billions of dollars’ worth of subsidies.

Flanked by local allies and executives from the company, Trump planted a golden shovel in the ground. “America is open for business more than it has ever been open for business,” he proclaimed in June 2018, as FoxConn promised to invest $10bn and hire 13,000 local workers.

Highways were built and expanded. Homes were razed. The area – a former manufacturing powerhouse – was primed for revitalization in a deal that seemed to underline the executive prowess of America’s most famous businessman, an image that has helped maintain many voters’ confidence that he could steer the US economy more competently than his rival, Kamala Harris, and could win him the White House again come November.

But on a recent drive around the site, fields of long grass and weeds stretched as far as the eye could see. Trees marked where houses used to stand. The Eighth Wonder was nowhere to be seen.

“Everyone was very skeptical it was going to happen,” said Wendy DeBona, a local Uber and Lyft driver, 53. “And then, of course, look what happened.”

Foxconn all but pulled the plug in April 2021, blaming “unanticipated market fluctuations” as it drastically cut back its plan and struck a new deal, through which it committed to spend $672m on a campus that would create about 1,400 jobs.

Today, a striking glass globe stands over what the firm did, eventually, build. What work is actually taking place there is the subject of local speculation; the company did not respond to a request for comment.

Trump had left office by the time Plan A fell through. “They dug a hole with those golden shovels, and then they fell into it,” Joe Biden, his successor, suggested earlier this year. “Foxconn turned out to be just that: a con.”

But one section of the site is a hive of activity, with cranes, diggers, trucks, lorries and tractors visible from the road. Biden himself visited in May, as Microsoft announced it would invest $3.3bn into a new data center on part of the land abandoned by Foxconn. The project is set to create 2,300 union construction jobs, and the tech giant has also pledged to build a new academy with a local technical college, through which more than 1,000 students will be trained in five years “to work in the new data center and IT sector jobs created in the area”.

So did Biden do what Trump didn’t? It depends on whom you ask. Who is better for the economy will be a crucial question in Wisconsin, a must-win swing state in the race for the White House. The state backed Barack Obama in 2012, Trump in 2016 and Biden in 2020. As Trump pledges to “rebuild” the US economy by cutting taxes, boosting wages and creating jobs, those attempting to persuade Racine county to reject him believe his role in the Foxconn debacle has shifted the dial.

“People in Wisconsin are pissed about Foxconn,” Kelly Gallagher, chair of the Democratic party of Racine county, said. “People in Racine county are mad about it. They know the money that was being spent. They know the people whose houses were bulldozed.”

Local party activists, knocking on doors across the county, want to paint the election as a simple choice between Republicans who failed to drive through one major project, and Democrats who delivered another. But even they concede this election is about far more.

“There’s no doubt that the economy has driven this campaign as pretty much the No 1 issue,” said Brandon Scholz, a former Republican strategist, who said many voters remain confused. “They’re being told inflation” – price growth – “is down,” he noted, and are left wondering why prices themselves aren’t going down, too.

But few people remain focused on Foxconn, according to Scholz, who said those who remain angry are more likely to blame the company than the Republican officials who courted it. “In this day and age with 24-hour news cycles and everything else, there’s been so much that’s supplanted the Foxconn story.”

Both campaigns see Wisconsin as a fundamental piece of the majority they each want to build. Harris flew to Milwaukee for her first campaign rally after Biden’s withdrawal, and broke away from the Democratic convention to return in August; Trump’s Republicans hosted their convention in the same arena.

The vice-president has appeared more willing to aggressively address voter concerns over the economy than Biden, who conceded that inflation had risen “slightly” during his presidency. Harris, by contrast, has said many prices are “still too high”, and put grocery store pledges at the heart of her policy agenda.

Price growth peaked at above 9% two years ago, its highest level in a generation. While it has since fallen back significantly towards 2%, many voters are still feeling the pinch. “Everything went up,” said Ernestine Brown, 48, who runs a catering business, and is unsure which candidate would help with the cost of living.

“Everybody says Trump is gonna make the economy better. I don’t know,” said Brown. Harris has also yet to win her over. “She’s just gonna be another candidate who’s gonna make a lot of promises that fall through.”

Inside the Regency Mall, a short drive from Mount Pleasant, Ahmed Joseph, 55, had served two customers in the 90 minutes after opening up the Gourmet Coffee House for the day. The economy is “down to the ground”, he said. “I’m stressed out, to be honest with you.”

Business had been going “down and down” since the pandemic, while costs rose. Thirteen years after opening the cafe, he might shut it down. “It’s not about the election. There’s nothing they can do.”

Others are more optimistic. Racine has “a lot of potential”, said Adam Booth, who recently opened a bookstore in the county’s namesake town. “But also … in terms of the local population, there’s a huge disparity between rich and poor.”

The election “feels like it could go either way”, he observed. “This area of the country, you do really feel that it is a swing state. It’s extremely polarizing through friends and families.”

Trump may still lead the polls on the economy, but there are signs that public perception of the inflation crisis is receding – which is good news for Harris.

Economic concerns came up more often on the doorstep six months ago than they do today, according to Gallagher, the Democratic activist. She pointed to a string of actions taken by the Biden administration to bring costs down in areas including healthcare, and suggested voters are more focused than the media on “actual, real-life issues” like abortion rights.

“Without the Affordable Care Act, I’d be living in a tent,” said Gallagher, whose husband broke his neck last year and was treated for cancer. The couple billed almost $1m to their health insurance provider in 2023. “I’m sick of the inflation talk,” she said, “because there are so many other issues that are making people’s lives, every day, easier, and more affordable. I’ll probably get in trouble for saying that, but it’s true.”

But many voters are still counting the cost of years of higher inflation – and the Trump campaign is certainly not over it. “I will end the devastating inflation crisis immediately,” the former president promised during his convention speech.

Trump has made promises in Wisconsin before, of course. Has his standing been affected by the crumbling of his Eighth Wonder? “Not really,” said Randy Bryce, a former ironworker and labor activist who ran for Congress in 2018. “People who support Trump believe anything he says.”

The Microsoft project, championed by Biden, is already having a “big impact” on the region, Nick Fick, of the International Brotherhood of Electrical Workers Local 430, said. “We have a lot of travelers coming in to work from across the country,” he added, “bringing money into the local economy, in terms of hotels, restaurants.”

This is not expected to budge many votes. “I don’t think Republicans are attributing the success of Microsoft coming here to the Democrats,” Kim Mahoney, who moved her home after years of litigation over the Foxconn development, and is now campaigning for Harris. “It’s like you can’t talk sense into these people.”

Robert Westmorland, 46, plans to vote for Trump in November. “The local economy isn’t doing very well,” he explained. Trump tried to get the Foxconn site, Westmorland noted, and create jobs. “It kinda backfired,” he added. “But he tried.”