The Foire aux Fromages et aux Vins in Coulommiers, an attractive town on the undulating Brie plateau an hour east of Paris, is a fabulously French affair: a monumental marquee, hordes of happy visitors and more than 350 stalls laden with Gallic bounty.

Among the cheeses are tomme from Savoie, crottins de chèvre from Aveyron, and great roundels of brie from nearby Meaux, alongside case upon case of chablis, Pouilly-Fumé, Nuits-Saint-Georges. And today, in amiable conversation with a local cheesemaker, there is Aymeric Chauprade, academic, author, consultant, and leading candidate in the European elections for Marine Le Pen's freshly fumigated Front National.

Here's the problem, explains an immaculately suited Chauprade, who besides degrees in maths and international law has a doctorate in political science from the Sorbonne: all this – he gestures around him as the throng prods, nibbles, squeezes, swills and swallows – is at risk.

Aymeric Chauprade, leading candidate for Marine Le Pen's Front National. Photograph: Jon Henley for the Guardian

These artisan French foods, proud produce of our terroirs and all protected by Appellation d'Origine status, will soon be at the mercy of multinationals, under the new transatlantic trade and investment partnership the European Union is negotiating with the US.

"American farmers and 'big food' will rule; our regulations and standards will count for nothing," Chauprade continues. "This is an EU that has no respect for national specificities; it's an EU of bureaucrats, of ever greater normalisation, in the service of big banks and corporations. It is not the EU we want."

Understandably, this message plays well here. But not only here.

Across the EU, insurgent parties from right and left are poised to cause major upset, finishing at or near the top of their respective national votes. As a result, rejectionist parties look set to send their largest contingent of anti-European MEPs ever to the European parliament: perhaps 25% of the assembly's 751 members. (Down from 766 in the current parliament.)

Does this matter? Dominated by the mainstream centre-right European People's party and centre-left Socialists & Democrats, which between them almost always muster a "grand coalition" of nearly 500 loyally pro-European MEPs, and with much of its work consisting of complicated compromises cosily worked out with envoys from the EU's other decision-making bodies, the European parliament does not function much like other parliaments.

Nor, although it now has a greater say over many more areas of EU law than before, are many European voters yet convinced of its relevance: while it supposedly represents some 500 million people, voter turnout among the 28 member states has fallen steadily since the first ever elections in 1979, when 62% of the electorate turned out, to just 43% at the latest vote in 2009.

But the near-certain election in a few weeks of a very substantial minority of MEPs actively working to derail, or at the very least disrupt, the parliament's work passing EU laws could come to be seen as something of a defining moment in the European project.

"I think," says Juri Mykkänen, a political scientist at Helsinki University, "that there is a lot of potential for these elections to become some kind of turning point for Europe, in large part because of the populist parties. I think the established pro-European parties are going to have to start listening. This has to be seen as a signal that for a lot of people in Europe, the European Union has gone far enough in this direction."

National sovereignty



Mykkänen's home country is a good case in point. Nervously sharing an 800-mile border with Russia, Finland had more reason to join the EU than most when it made the leap in 1995.

"For us, the EU actually offered a better chance of national sovereignty," Mykkänen says. "That's a big deal for us: we've only had it since 1917. Except it has been a false promise. Then there's the financial crisis, having to pay for other people's mistakes … Support for the EU is falling."

Capitalising on that growing sense of disillusion is the Finns party. In national elections in 2011, stealing votes from right and left, the Finns' fiscally leftwing but socially conservative and unashamedly nationalist platform – it supports the welfare state and marriage, and strongly opposes immigration – saw it capture nearly 40 seats in the Finnish parliament. Currently polling at about 18%, it could field up to a quarter of Finland's 13 MEPs.

"There's a vicious circle in the EU," says Jussi Halla-aho, one of its leading MPs and a European parliament candidate MEP, in a striking brick-and-glass annex of the Helsinki parliament. "Integration creates problems, so more integration is proposed to solve them."

Not that Europe is altogether "a hopeless case", he adds, his words chosen carefully. "It has tools and instruments that bring added value to everyone. I accept its existence. But it has to focus on the functions that are beneficial for everyone … and not on political integration. Political integration, in my view, does not serve the interests of the nation states that make the union."

Freedom party (PVV) leader Geert Wilders. Photograph: Michael Kooren/Reuters

If the Finns party is polling high on its anti-EU ticket, others are doing even better. The Front National, on about 24%, seems comfortably on course to win at least 20 of France's 74 seats. Nigel Farage's europhobic Ukip, which according to the most recent poll enjoys more than 30% support from those who say they will definitely vote, should also finish top or a close second, and seize a similar number of the UK's 73 seats.

In Denmark the anti-immigrant Danish People's party is ahead on 27%; Austria's Freedom party (FPO), which campaigns against "Islamisation", is on track for 20% of the vote; Geert Wilders' anti-EU, anti-Islam Freedom party (PVV) was leading in the Netherlands until its controversial founder triggered a public backlash – and several resignations – by publicly egging on people chanting against Moroccan immigrants. It could yet bounce back.

But anti-EU sentiment is not solely the preserve of the xenophobic, the nationalist, or even the somewhat socially conservative right. True, if parties such as the Front National are making strenuous efforts to ditch their past (and its young, highly qualified and personable candidates have now made the party most popular in France among 18- to 24-year-old voters), some anti-Europeans remain indelibly nasty.

With 18 seats in the Greek parliament, Golden Dawn may reject the neo-Nazi label, but its emblem bears a strong resemblance to the swastika, its leaders are prone to giving Nazi salutes, and six of its MPs are in jail accused of using the party to run a criminal gang.

Similarly, Hungary's Jobbik, which took 20% of the vote in April's general elections, may prefer the term "radical nationalist", but its ideology is so freighted with antisemitism, racism and homophobia that far-right groups in western Europe, including the Front National and the PVV, steer well clear.

As the continent struggles to emerge from its economic crisis, distrust and disillusion with Brussels are now fuelled by more than the spectres that have traditionally haunted the more thuggish elements of Europe's far right.

To older fears about loss of sovereignty, mass immigration and (more recently) the rise of Islam have been added an equally potent anger about bitter austerity, rampant unemployment and inequality – a cocktail that means contemporary Euroscepticism is alive across the political spectrum.

These Euro-insurgents appeal to people unsure about their own future, worried about where their country is going and whether they belong there, and doubtful that mainstream parties can or will do anything about it. With little sign of any real fall in unemployment or serious economic recovery, that's a lot of people.

Disillusion with the EU, certainly, is at record highs across the continent. The surveys are unequivocal: 60% of Europeans "tend not to trust" the EU now, against 32% in 2007; in 20 of the 28 member states a clear majority feels the EU is going "in the wrong direction"; for the first time, Eurosceptics outnumber supporters by 43% to 40%.

"In our analysis, the real turning point came in the late 1980s, when the big industrialists started laying down the plans for the future of Europe," says Dennis de Jong, a leading MEP from the impeccably leftwing but fiercely Euro-critical Dutch Socialist party. "Until that moment, the EU seemed like a logical post-war development. But industry, not ordinary people, has driven much of what's happened since, from opening internal borders to the euro. This EU – the EU of multinationals, of harmonisation – makes people uneasy. People like difference. They like identity."

Coming from a polar ideological opposite, the words bear a striking similarity to those used by the Front National. But left and right see eye to eye, too, in their verdict on Brussels.

Socialist De Jong says: "Power is concentrated there, and it is growing all the time – like every bureaucracy, Brussels feeds itself. And so every problem has to have a European solution."

And this is the Front National's Chauprade: "It's the bureaucrat's dream: a completely uniform, formatted Europe. Never mind that the EU was founded on the idea of subsidiarity, of no one telling anyone else what to do. It's hard for them to admit – they've devoted their lives to building it. But this EU is not serving its citizens."

Beppe Grillo, leader of the anti-euro Five Star Movement in Italy. Photograph: Alberto Pizzoli/AFP/Getty Images

Similar views prevail on the radical left in Greece, where Syriza could finish top of the European poll. The party has yet to translate into concrete European policies the fiercely anti-EU, anti-austerity message that made it the largest party in the Greek parliament in 2012, but it is unlikely that the eight or nine MEPs it could have will feel particularly warmly towards the European commission.

In Italy, too, comedian Beppe Grillo's anti-establishment, anti-corruption and anti-euro Five Star Movement, consistently polling above 20%, could easily capture up to 20 of the country's 73 European parliament seats. It has promised to wade in and "shake up" Brussels.

"What we mean by that," explains Manlio di Stefano, a Five Star MP, "is that the EU has to return to its original concept. Not a union but a community, based on principles of solidarity and dignity. We are saying that we must renegotiate the Europe we have, or we cannot stay. We cannot exchange our people's dignity for an agreement to stay in Europe."

Perhaps most remarkably of all, pretty much the same anti-EU song – set to an only slightly different tune – is now being sung even in Germany.

In a cavernous conference centre on the outskirts of the handsome east German town of Erfurt last month, some 1,500 people gathered for the congress of Alternative für Deutschland. Formed barely a year ago by a mild-mannered professor of macroeconomics at Hamburg University, Germany's newest political organisation does not pull your usual protest-party crowd: there are college lecturers, lawyers, doctors, judges, academics, company directors. More than 70% have never been members of a political party before.

"We are the revolt of the reasonable people," says Frauke Petry, chemist, businesswoman and an AfD spokesperson. "We'd like to get back to the basics of the community. We think the EU has lost sight of its fundamental freedoms, with this never-ending harmonisation – for which Germans fear they will end up paying." (Germans have no problem with Greek civil servants wanting to retire at 50, she adds, as long as they do not have to meet the cost.)

Loss of identity



There's more, and it sounds quite familiar. "We think the commission is pulling more and more rights to Brussels," Petry says. "We think that while Germans are very, very patient, they are starting to feel they are losing their identity. And although that is naturally rather a sensitive subject in Germany, they don't like it. We think it's wrong that there are subjects – Europe, immigration controls, national responsibility – that cannot be discussed in Germany, because it is not acceptable."

As a party founded by an economist, though, Alternative für Deutschland – which is now looking at up to 10 seats in the European parliament – thinks above all that something has to be done about the euro. "It is clearly harming Europe," says Jörg Meuthen, an economics professor from Kehl and European parliament candidate. "In this party we are about facts, evidence, reason. Not ideologies. And the clear facts, we have to face it, are that while the common market is a success story – it works, it has increased prosperity, it has brought us together – the common currency is precisely the reverse. It does not work. It has reduced prosperity. It is pushing us apart."

Nigel Farage, leader of Ukip, which wants Britain to walk away from the EU. Photograph: Christopher Furlong/Getty Images

One of AfD's democratically chosen slogans, says another candidate, Dirk Driesang, is "less EU, more Europe". "Solidarity is important," he says. "But on Greece, the EU showed solidarity with the banks, not with the Greek people. The euro's a problem that can't be fixed. It's political will trying to trump economic reality."

On this, almost all the insurgents agree: FN, Finns, AfD, Five Star, Dutch Socialists – the euro, they argue, has been a disaster. "As an experiment, it's been a catastrophe," says Ludovic de Danne, European affairs adviser to Marine Le Pen. The currency is "structurally unstable", says De Jong.

"We quite clearly should not be in the same currency as Greece, Italy and Spain," says Halla-aho. "It is not based on financial realities. It was a nice idea to think the euro would push countries like Greece to raise their game, but it hasn't happened. And the euro is far too strong now for Finland, which depends almost entirely on exports."

Where they fail to agree, however, is on what to do about it. The Front National would like France out the euro, and to hell with the consequences. The Dutch Socialists want "serious and open discussions, among all member states, about how to dissolve it in an orderly manner".

AfD quite likes the sound of a smaller, northern eurozone, made up for example of Germany, Austria, the Netherlands and Finland. The Finns think some countries should leave, but aren't sure yet who: the southern states, or themselves.

Divisions over the common currency are mirrored in other equally fundamental areas. Ukip, for instance, wants Britain to simply walk away from the EU, regardless; the FN and PVV would go the same way given half a chance; AfD and the Finns see their own countries' exits as unthinkable, even suicidal, urging – like many continental sceptics – structural reform and the rebuilding of a kind of enhanced, free-trade community of sovereign states instead.

Several anti-Brussels parties, including the Front National and the Dutch Socialists, propose denying the unelected and – as they see it – centralising, ultra-liberal, bought-up and sold-out commission the right to initiate legislation, giving it instead to MEPs and the Council of Ministers representing national governments. Many, too, want a more flexible union, with member states able to say no to specific measures.

On other issues they face fundamental disagreements. Questions around immigration, "Islamification" and identity politics are no-go areas for many: Marine Le Pen and Geert Wilders may recently have agreed to form a continental anti-European alliance aimed at wrecking the EU from within, and other hardline nationalists such as Italy's Lega Nord, Austria's FPO, Vlaams Belang in Belgium and the Swedish Democrats may well join them, but more moderate parties will not go near.

"Wilders and Le Pen are simply out of the picture for the Finns," says Sakari Puisto, a young academic standing for the party in Tampere, in central Finland. "We could not envisage allying ourselves with neo-fascists. Or with communists, for that matter."

Unity against EU



De Jong says his party "will not engage with anyone proposing discriminatory policies, wanting to create tensions on the grounds of race or religion". Farage has said that while he admires Le Pen's drive to decontaminate her party, the whiff of historic antisemitism that still hangs over it rules out any formal co-operation with Ukip.

Unfortunately, formal co-operation is important in the European parliament: forming a political group, which needs 25 MEPs from seven states, qualifies its members for offices and funding – as well as, crucially for any party pushing for change, a say in what gets debated in the parliament's plenary session, the right to table motions for resolutions and chair parliamentary committees, and extra speaking time in the chamber.

Will the insurgents manage to overcome their differences long enough to form an effective opposition to the pro-integration behemoths of centre-right and centre-left – to become, in effect, a kind of European Tea Party, paralysing the European parliament in much the same way as ultra-conservative Republicans have paralysed Washington?

While all stress "flexibility" and willingness to co-operate with anyone who shares a specific view, few can imagine Syriza ever sitting down with the FPO, AfD with Jobbik, or Ukip with the PVV. Most EU observers seem to think the Wilders-Le Pen group stands a fair chance of hanging together, however, and the current Europe of Freedom and Democracy group – which includes Ukip – will almost certainly re-form with new and different members. The radical left, too, should comfortably form a group.

A demonstrator burns an EU flag in Nicosia, Cyprus. Photograph: AFP/Getty Images

Whether that will be enough for the rebels to seriously challenge the status quo is another matter. "At the end of the day," points out Hugh Bronson, an AfD candidate, "even if the combined anti-Brussels forces – I don't like to say Eurosceptic, we're not all anti-EU, just anti this particular EU – even if we manage 25 or 30% of seats, the Christian and Social Democrats will still have 70%. It could just be business as usual; same old, same old …"

Some observers feel the anti–EU parties' best chance of really influencing debate over the coming years is at a national level.

Perhaps the clearest example of this is in Britain, where Ukip, despite not having a single seat in Westminster, has parlayed a string of strong byelection performances and the winning media persona of its hail-fellow-well-met leader into real political gain, pushing David Cameron into pledging a referendum on Britain's membership of the EU and rushing through measures to reduce "unwanted" EU immigration in the form of so-called "benefit tourism".

But in the Netherlands, too, Wilders' anti-Europeanism has contributed to growing Dutch dislike of austerity and secured clampdowns on immigration and asylum-seekers, while in France the Front National, after a carefully planned and efficiently implemented local campaign that targeted winnable town halls and concentrated more on policy credibility than outraged protest, has both the ruling Socialists and the opposition UMP running scared.

Even in Finland, notes Halla-aho with the satisfaction of a man who has got at least some of what he wants, "the best way to make a politician act in a certain way is to make him fear the results of the next election".

It is at the heart of Europe, though, that these parties want to make their mark. "I really hope the established parties listen after this shock; they really have to," says Di Stefano of the Five Star Movement. "The fact that so many political parties, of such wildly differing ideologies, now share such a fundamentally similar analysis of where the European Union is failing – that, surely, is a measure of how far things have gone wrong. It's going to have to change."

And if Brussels does not listen, the rebels believe, there will, eventually and inevitably, be an explosion violent enough to blow the whole European construct to pieces. "If we are ignored," says the Dutch socialist De Jong, "then in five years' time, our voice will be even louder. People will be even more angry and frustrated."

Back in Coulommiers, Chauprade's European affairs adviser, Adrien Mexis, 33, a lecturer in European law at the prestigious Sciences Po in Paris, former staffer at the European commission in Brussels, and newly elected Front National local councillor, is harsher still.

"I spent six years in Brussels," he says, "where we were supposed to be defending the interests of the people of Europe. Instead, we defended the interests of the lobbyists, big industrial groups and multinationals. We defended ever-deeper integration and ever-wider federalism; a uniform, homogeneous Europe, devoid of identities.

"Is that really what the people of Europe want? I don't think so. And I think they're waking up to it. This is a big moment."