As surely as the toll echoes from Big Ben, every nationwide election in Britain for more than a century has been won by one of two parties: Labor or the Conservatives.

Next week, that august record is likely to come crashing down, courtesy of a far-right insurgent party that has seized on a pervasive anti-immigrant and anti-establishment mood to rocket to the lead in polls for the European parliamentary election.

The rise of the U.K. Independence Party has shaken up British politics in a way rarely seen here. While far-right parties have long been influential across continental Europe, they have always been relegated to the fringe in this country, which sees itself as open and inclusive.

But the political and economic stars have aligned in UKIP’s favor, and a party that’s dismissed as racist, xenophobic and a bit loony by London sophisticates suddenly is steering the national debate with its calls for Britain to close down borders and leave the European Union. A victory in European elections would confirm its newfound status as a major political player, even though UKIP lacks a single seat in the British Parliament.

The party’s message has resonated particularly well in struggling small towns and decaying industrial centers, where the benefits of a recovering economy are scarcely felt and where mainstream politicians are seen as out of touch with constituents furious over a massive influx of foreign workers.

“We’ve gotta get control of our country back,” said Gordon Harris, a youthful-looking 73-year-old with a skull tattooed on his forearm. “I’ve got nothing against immigration, but it’s just too much. It’s out of control, and we can’t cope.”

For decades, Harris was a truck driver and a Labor voter. But one recent night, he turned out at a conference center in this genteel Cambridgeshire market town to cheer Nigel Farage, who as UKIP’s leader has become the nation’s preeminent channeler of anti-establishment vitriol.

The party’s emergence doesn’t just challenge the ruling Conservatives, who have scrambled to the right on immigration and environmental policies to keep from being outflanked. As Harris’s conversion shows, it also threatens to eat into support for Labor, which risks losing the backing of working-class voters alienated by the party’s progressivism.

UKIP’s appeals to the Reagan Democrats of Britain are hardly subtle: On one campaign billboard, a dejected worker sits on the curb with a coin cup at his feet. “British workers are hit hard by unlimited cheap labor,” reads the ad’s text.

The message is typical of a European election campaign that has been dominated in Britain by voters’ fears, not their hopes.

“UKIP promises a better yesterday,” said Peter Kellner, president of the polling firm YouGov. “The appeal is to people who feel that Britain has become a less attractive, less secure and more frightening place. They dislike the modern world and want to get off.”

The party has traditionally done well in European elections, which are held every five years to select the 751 members of the European Parliament. The elections are marked by low turnout, and UKIP has struggled to translate its success in the European vote into success where it most counts: British parliamentary elections. But the party, which has been around for two decades, has never done as well in the polls as it is doing now.

‘Different Britains’

Farage, UKIP’s leader, is a somewhat unlikely champion of the working man. He made a small fortune as a commodities broker in London’s financial district,and for the past 15 years has been employed on the taxpayer’s dime as a member of the European Parliament — a job he wants to eliminate. His German-born wife also earns a government salary working as his secretary.

But Farage is a gifted salesman whose breezy style and ear for a sound bite would not be out of place on American talk radio — or in the local pub, where he often campaigns, pint in hand. That sort of everyman quality places him in marked contrast with the stiff and remote Oxbridge-educated politicians who dominate the Labor and Conservative parties.

And it serves him particularly well when talking about immigration, an issue that polarizes the British electorate like few others.

In cosmopolitan London, immigration is widely seen as a virtuous driver of economic growth and cultural vitality. But here in rural eastern England — where jobs working the fields have been a magnet for Lithuanians, Portuguese and others from across Europe — immigrants are seen as a drain on public services and as competition for housing and employment.

“There are two completely different Britains. There’s London, and there’s the rest of Britain. Attitudes are very different,” Farage said in an interview before taking the stage for the UKIP rally here. “Nobody in this country has voted for 4 million immigrants to come here in the last 15 years, and for probably another 3 million to come between now and 2020. There’s unrecognizable change happening in our country. The life prospects and job prospects, particularly of working-class people, have been severely dented.”

Farage’s solution is for Britain to exit the European Union, a body that by law allows citizens of all 28 members to move freely across the bloc. In the past decade, the expansion of the E.U. into eastern Europe and the economic crisis that has roiled southern Europe have made Britain an especially attractive destination, and millions have made the journey.

The influx began during the Labor government of Tony Blair and has continued unabated under Tory Prime Minister David Cameron, despite pledges by Cameron to sharply reduce the flow. Farage argues that until Britain leaves the E.U., no government will be able to claim control of the nation’s borders.

“What we’ve done is say to 485 million people, ‘You can all come, every one of you,’ ” Farage said, referencing the total population of the E.U. “ ‘You’re unemployed? You’ve got a criminal record? Please come. You’ve got 19 children? Please come.’ We’ve lost any sense of perspective on this.”

Getting valuable momentum

Critics accuse Farage of pandering to anti-foreigner sentiment, and the party has come under assault in recent weeks for overtly racist comments made by its members. In one case, a local council candidate tweeted that a black comedian should emigrate to “a black country.”

On Tuesday, a prominent young UKIP activist who is of Indian heritage abruptly resigned, saying the party had lost its way by blaming foreigners for the struggles of ordinary Britons.

“The direction in which the party is going is terrifying,” wrote Sanya-Jeet Thandi in an article for the Guardian newspaper. “UKIP has descended into a form of racist populism that I cannot bring myself to vote for.”

Farage has been forced repeatedly to deny that UKIP has a problem with racism. He has said that UKIP will not go form a coalition with other far-right parties in Europe — several of which also are expected to do well in this month’s vote — because he disapproves of their policies and language on race.

The criticism has done little to dampen enthusiasm for the party, and indeed may be feeding it by confirming for many alienated Brits that the elites are out of touch.

Matthew Goodwin, author of a book that chronicles UKIP’s rise, “Revolt on the Right,” said that if the party finishes first in the European elections, the outcome “will amount to a complete rejection of the British political class.”

It also will give UKIP valuable momentum going into next year’s elections for the British Parliament — momentum that Farage already seemed to sense as his speech in St. Ives neared its finale.

“Are you prepared to join our people’s army that will topple the establishment on May 22?” he shouted to a packed auditorium.

The crowd of 700 backers clad in UKIP purple rose to its feet and roared its response.