Just over two months ago, the small Dutch community of Almelo woke up to a tragedy that turned out to have national repercussions. On a modest street in a rundown area, Aziz Kara, a 64-year-old Turk, became embroiled in a ferocious argument with his neighbours. When he was struck to the ground, the impact of the blow put him into a coma. Ten days later Kara died of a brain haemorrhage.

In normal circumstances, the death would have preoccupied only the local media. But as the Netherlands prepares for its second national election in two years, Kara's case was different. When relatives and the local community organised a silent march through the streets of Almelo, politicians and mourners came from The Hague and across the country. National newspaper columns were devoted to the incident, which quickly became a PR disaster for arguably the most influential far-right politician in the European Union, Geert Wilders.

To Wilders's acute discomfort, the man who allegedly beat Kara to the ground was called Henk. And his wife – who apparently shouted racist abuse at the victim on the ground – was called Ingrid. The resonance of the names was lost on no one. In the last two years, the Netherlands has learned to live with another "Henk and Ingrid" – a fictional couple born of Wilders's own populist imagination. Just as Basildon man and Worcester woman became stars of elections in Britain, Wilders's blue-collar caricatures were successfully deployed to voice the anti-immigrant, anti-Islam sentiments of his Freedom party (PVV). "Henk and Ingrid are sick of paying for Ali and Fatima," went one anti-immigrant slogan.

After Kara's death that didn't sound so good. "Henk and Ingrid are real," tweeted one TV personality. "And they just killed someone in Almelo."

Wilders has since dropped all reference to Henk and Ingrid. But the backlash against the PVV after the killing indicated that its culture war with Islam is no longer making the political weather in Holland. Wilders, the divisive, charismatic showman of national politics, is projected to take only 18 of the 150 available parliamentary seats on 12 September, well down from 24 two years ago.

"Those Wilders cultural themes are not dominating the public debate," said Chris Aalberts, a cultural historian at Erasmus University in Rotterdam. "The big election issues right now are economic – health, social security … and Europe".

It is a change that could have huge consequences for the eurozone's political landscape at a delicate moment. For control of the Oranje zeitgeist has not returned to the handful of mainstream national parties which traditionally form coalitions in the Hague. Instead, as austerity bites hard even in this prosperous northern bastion of the eurozone, the newest political insurgency to sweep the Netherlands is coming from the radical left.

The Dutch Socialist party (SP) is an organisation once known for its Maoist sympathies and habit of throwing tomatoes at political opponents. It now finds itself within touching distance of becoming the biggest parliamentary force, eclipsing its more moderate rivals in the Labour party and on course to gain at least 30 parliamentary seats. Just as the unexpected success of the leftwing Syriza party in beleaguered Greece set alarm bells ringing in Brussels, the SP has become another surprise package of European politics at a time when more centrist politicians seem to lack ideas.

While Wilders's party made its name through divisive ideas such as a tax on Muslim headscarves, a favourite SP slogan reads: "There's enough to go round for everyone." But that inclusive message is intended to carry menacing implications for bankers, business and the EU powerbrokers of Brussels. Anti-austerity and exasperated by endless eurozone bailouts, the SP's leader, Emile Roemer, 50, has pledged to abandon the government's plan to bring the budget deficit below 3% by 2013, largely through healthcare cuts and wage freezes, and face down German chancellor Angela Merkel and the European commission if they object.

Conservative plans to extend the retirement age from 65 to 67 would also be torn up. And in an echo of French president François Hollande's intention to raise more money from the very rich, income tax would be raised from 52% to 65% on those earning above £119,000 a year. A public investment programme, partly financed by the proceeds, would be aimed at turning around the ailing Dutch economy.

For an avuncular former teacher, known for a toothy smile and sometimes nicknamed "Fozzie Bear", it adds up to an uncompromising platform designed to cause palpitations in both the Amsterdam stock exchange and European commission corridors.

On Europe, Roemer has still more to say. A eurozone banking union has been ruled out, as has the so-called European stability mechanism (ESM), which would allow fines to be imposed on countries refusing to maintain balanced budgets. There would be no more Dutch agreement to bailouts of Greece, or any other country.

For a once-marginal party that used to stay out of parliamentary politics, this twin strategy – targeting cuts at home and bailouts abroad – has struck a deafening chord. The Netherlands no longer feels like a safe haven in the eurozone storm. In May, the European commission predicted that the economy would contract by nearly 1% this year. House prices are falling at an alarming rate and in July the rating agency Moody's publically contemplated a downgrade of the country's cherished triple A rating on government debt.

Many voters have had enough. In one poll, some 70% expressed a preference for greater economic stimulus and fewer cuts in 2013. Another survey found that only 58% of Dutch people were now in favour of EU membership, compared with 76% in 2010, a drop that represents a major wobble in one of the founder members of the EU.

Over a few months, the mild-mannered Roemer has transformed the political debate. Prime minister Mark Rutte has taken to warning that an SP-led government would imperil the country. "The SP has the economic themes," said Aalberts. "And the foreigners Dutch people are concerned with at the moment are Polish and Greek, not Muslim."

There was ample evidence of that at the Wesselerbrink market in Enschede, where the SP was doing a thriving trade in symbolic foam "protest" tomatoes, handed out to passersby in one of the city's poorer areas. In this eastern city, which boasts a proud industrial heritage but has a highly uncertain future, the talk among the shoppers was of medical charges, money worries and the malign influence of Brussels bureaucrats and profligate Greeks.

"I worked until I was 43," said Kim Bozuwa, who needs a "scootmobile" to get around. "Then I smashed my kneecap in a fall. I've also got diabetes. If the Conservatives win, I'm going to have to pay far more in payments for my medical care. Why? It's not as if I can choose whether to have the medication or not."

Lillian, a pensioner who has lived in Enschede most of her life, was also contemplating a vote for the SP. "I've already got a reduced pension thanks to the crisis," she said. "I can't see why we should take orders from Brussels to cut our living standards. Half of the bureaucrats there do nothing that's any use to anyone and half are on the make. It's an elite mafia. And the Greeks lied to enter the eurozone. They altered their figures to make sure they got in."

Wim Kooiker, a market regular, echoed her sentiments and went a step further. "The Netherlands should get out of the EU. First it was Greece that needs the bailouts, then Spain, soon it will be Italy and then it will be France. We should get out and so should England!"

This month promises to be tumultuous for the eurozone. On the same day that the Dutch vote, a German constitutional court will rule on the legality of a formal rescue fund for euro members, amid mounting fears of a Greek exit. An anti-austerity uprising in the Netherlands would add to the sense that Europe's policymaking elite has lost its way.

Could it happen? With no experience in national government, Roemer struggled in the opening televised debates. It is possible that even if the SP scores a resounding success at the polls, centrist parties will combine to ensure it is excluded from any coalition. But the message of the Dutch election campaign of 2012 is unmistakable. In yet another eurozone country, a huge disconnection has emerged between popular sentiment among voters and the policy consensus maintained by a beleaguered political elite.

In Greece, Syriza and its leader, Alexis Tsipras, drew the benefit. In Italy, a maverick comic named Beppe Grillo has become the most popular political figure around. In Holland, a temptation to ditch austerity and go it alone is changing a political landscape dominated for 10 years by multiculturalism and race.

As the owner of an engineering company in Enschede, Uulke Visser makes for an unusual SP activist. Unsurprisingly, he admits to a sense of excitement as an extraordinary campaign comes to a climax. "This party stands for the opposite of 'what's in it for me?'. It's about investing in people and their prospects. Here in the Netherlands we have a group of people who are getting desperate. They're asking, 'Is this all we can expect?'. And they're thinking things will only get worse. It could yet be the biggest moment in the history of the Socialist party."