U.K. Independence Party leader and parliamentary candidate Paul Nuttall, center, campaigns in Stoke-on-Trent the day before the election to fill a vacant parliamentary seat. (Michael Robinson Chavez/The Washington Post)

For hundreds of years, this small-scale city in England’s industrial north has been synonymous with pottery — colorful plates, bowls and tiles fired by workers in the heat of the local kilns and sold in fine ceramics shops the world over.

But come Thursday, Stoke-on-Trent could be known less for shaping crockery than for smashing it.

The British political order, virtually unchanged for a century as the Conservative and Labour parties have traded control, is under threat of a populist-infused realignment as the U.K. Independence Party seeks to capitalize on its success in last year’s Brexit campaign.

Having helped to push Britain toward the departure lounge of the European Union, the anti-immigration UKIP is now seeking to displace Labour as the country’s natural home for working-class voters.

And a Thursday election here to fill a vacant parliamentary seat, while minor in the overall calculus of British power, could be a telling indicator of just how far the country’s politics have shifted in Brexit’s wake.

To the right-wing UKIP, the seat represents a prime opportunity to break through with working-class voters who have for decades habitually backed the center-left Labour Party but who feel increasingly disconnected from the party’s cosmopolitan, white-collar outlook.

Known for its pottery — the area is blessed with exceptional clay — Stoke still produces vast quantities. But its once-burgeoning coal industry has disappeared, and the area’s tidy central shopping district is pocked with vacant storefronts.

Like Rust Belt residents who helped deliver the White House to Donald Trump, Stoke’s working class last year defied the pleas of Labour leaders who advocated for Britain to stay in the E.U. and instead made this city “the Brexit capital of Britain” — with nearly 70 percent of voters opting for “out.”

Now UKIP is hoping to convert those Brexit voters into supporters and in the process win just its third parliamentary seat since its founding nearly a quarter-
century ago.

“Politics is changing,” said Paul Nuttall, a mild-mannered academic who succeeded the bombastic Nigel Farage as UKIP leader and is campaigning to represent Stoke. “It’s not just changing in this country. It’s changing all over the world.”

Unlike Farage, who focused UKIP firepower in the more traditionally conservative country landscapes of southern England, Nuttall has zeroed in on the struggling postindustrial centers of England’s north. Traditionally Labour strongholds, they have become vulnerable as the party has become more detached from its roots, Nuttall said in an interview at the party’s purple-streaked offices in the city’s center.

“The Labour Party is more ­London-centric than it’s ever been. They talk about the issues that may concern an Islington dinner party — climate change, Palestine, free trade, human rights,” Nuttall said, referring to the trendy north-London neighborhood that happens to be home to Labour leader Jeremy Corbyn. “But those are not the issues on the doorstep in working-class areas. Those issues are immigration, cutting foreign-aid budgets, law and order, and putting British people first.”

The echoes of Trump are no accident, even if Nuttall insists that, unlike Farage — an enthusiastic Trump booster — he didn’t support the New York billionaire.

UKIP is hoping to use at least part of the Trump playbook and ride a populist wave to power.

But Labour has recognized the threat and is waging a determined battle to keep a seat it has held for nearly 70 years from falling into the hands of the far right.

“This is a defining moment,” said Jack Dromey, a Labour member of Parliament who is directing the party’s campaign here. “It’s the moment where either UKIP breaks through or we turn the tide” against “a grotesque populism purporting to be the party of the working class.”

Dromey, a former union leader, said voters in areas such as Stoke were right to feel discontent with a political establishment that hasn’t always defended the interests of the working class.

“There’s a distinct pride in Stoke. There’s also a sense that Stoke is not the city it once was,” he said as party activists rushed in and out of party headquarters bearing stacks of red Labour leaflets. “I understand why people feel the way they do.”

But he depicted UKIP and Nuttall as opportunists, seeking to capitalize on the working class’s grievances for their own gains.

“UKIP is a party with no answers,” he said. “They simply seek to exploit discontent.”

Analysts say the outcome of Thursday’s contest is impossible to predict, with Labour, UKIP and even the ruling Conservatives jousting over a seat that is normally so comfortably in Labour’s column that a vote count is hardly needed.

Rob Ford, a University of Manchester political scientist who co-wrote a book on UKIP, said that Stoke, with its high concentration of white, working-class and less-educated voters, is exactly the sort of seat UKIP has long coveted.

“On paper, it’s an area where UKIP should do well,” he said.

But paradoxically, its success in pushing Britain toward Brexit — and Prime Minister Theresa May’s insistence on following through on UKIP demands for a clean break with Europe — may have blunted the party’s appeal. By promising to deliver on UKIP’s core demand, May and her ruling Conservative Party have co-opted the anger that fed last year’s referendum vote, at least for the time being.

“The large dissatisfied and distrustful element is still out there. It’s just that they’re unusually happy right now,” Ford said. “They won’t stay that way for too long.”

If UKIP comes up short in Stoke, it would mark a significant setback to Nuttall’s strategy of broadening UKIP’s appeal by targeting working-class voters. The UKIP leader — who was Farage’s longtime deputy — has already been damaged by claims he inflated his connections to the 1989 Hillsborough disaster, when 96 soccer fans were crushed to death at a crowded stadium.

But in many ways, Labour and its leader, Corbyn, have more on the line. The party is suffering from historically bad polling figures that, should they hold, point to a Tory rout in the next general election, in 2020.

On Thursday, Labour faces the prospect of losing not only Stoke but also another traditionally safe Labour seat, Copeland, where the Tories are running hard.

Corbyn, who shocked Britain by emerging from the far-left back­benches to become party leader in late 2015, has been unable to satisfy the party’s pro-E.U., progressive wing or its Euro­skeptical, working-class base. If his party loses both seats Thursday, Labour could drift even further into the political wilderness.

“Corbyn is not their only problem,” Ford said. “But he’s made all their problems worse.”

Those problems are easy enough to see on the streets of Stoke.

To Peter Doyle, a cheerful pub and hotel owner, Corbyn is “a waste of space” who hasn’t used his role to defend Britain from the most dire impacts of Brexit. Instead of Labour, which sometimes gets his vote, Doyle will be backing the ardently pro-E.U. Liberal Democrats.

“I’m in business,” Doyle said. “I’ve just come through one of the biggest recessions in British history. I don’t want to go through another one.”

But to Graham Patrick, a longtime pottery worker who is now retired, Labour’s opposition to Brexit marks it as out of touch.

“Labour hasn’t done much for us,” said Patrick, who wore a faded blue Yankees cap with a purple UKIP rosette pinned to his chest as he walked through the pedestrianized city center Wednesday. “I just want a change. That’s all.”


Karla Adam in London contributed to this report.