Disgruntled Irish villagers threaten to derail an entire continent

It isn't much to look at – a glum smattering of pubs and bungalows on the fringes of Dublin's ever-widening commuter belt. Sleepy, drab and, despite its proximity to the capital, unambiguously rustic, the tiny village of Prosperous – population 500 – epitomises an Ireland that is rapidly fading into the figurative murk.

The parish church, once a social and moral epicentre, is half-obscured by a recently erected community hall. People carriers and all-terrain vehicles have begun to outnumber muck-spattered tractors and cattle trucks. City folk are staging a silent takeover, and many locals believe their way of life is being driven to extinction – but the old, dwindling Prosperous may yet wreak its revenge.

On Saturday, Ireland votes again on the Nice Treaty. It is the only European Union state that has not ratified the document (it is also the only one that has put it to a referendum), which lays the framework for the accession of up to 10 new countries into the EU. A second Irish "no" vote would delay – and possibly derail – Brussels' vision of a greater EU, encompassing 25 states and straddling the continent.

The pro-Nice lobby, headed by the political and business mainstream, warns that in such circumstances the Republic will find itself an international pariah, plunged into an economic wilderness. Anti-Nice campaigners, a rag-tag affiliation of environmentalists, republicans, Catholic fundamentalists and anti-globalists, say the treaty threatens Irish democracy, undermines its cherished tradition of military neutrality and may prompt increased migration from eastern Europe.

With the electorate split, it is increasingly apparent that the rural populace will have a significant say in the outcome. Prosperous, and innumerable disenfranchised communities like it, could determine the fate of Ireland – and shape the future course of Europe.

Emerging from O'Connor's grocery, clutching a bale of peat briquettes, Paddy Cleary embodies the conservative rump expected to come out in force on polling day. Mr Cleary, a pensioner, is alarmed at predictions by the right-wing "No to Nice" organisation that ratification would attract thousands of unskilled migrants from former Soviet bloc nations. Justin Barrett, the group's hard-line Catholic leader, warns a "yes" vote would dilute public morality and weaken national identity, and could even force the government to legalise abortion.

Mr Cleary is adamant – Europe should keep its nose out of Irish affairs. "I think we're better off keeping them at arm's length," he said. "What's wrong with being isolated? It protects you from outside interference and lets you do things your own way."

At Dowling's pub, patrons blame the government for fomenting hostility to Nice. John Sheehan, an accountant forced by Dublin's spiralling property prices to relocate to the rural hinterland, believes many people will vote "no" to signal their disapproval of the administration's recent litany of own goals.

Despite his disgruntlement with the government and his suspicion that adoption of Nice will draw Ireland into an unwanted European military alliance, Mr Sheehan supports the treaty. He fears that failing to sign would damage the country's international standing and sap foreign investment.

Mr Sheehan voted Green at the last general election, but he is angry that in climbing on the anti-Nice bandwagon, the party has joined an unlikely jumble of extremists which includes not only the Catholic right and unreconstructed Marxists, but an ascendant Sinn Fein, which now has five seats in parliament. Although Sinn Fein's case for a "no" vote isn't particularly distinctive – it claims a re-run of last year's referendum makes a mockery of democracy and warns Ireland will lose influence in a larger EU – it has campaigned with a vigour and flair rare in the cosy, consensus-driven world of Irish politics.

Colin Boyle, a young businessman visiting McCarthy's hardware store, personifies the confident and affluent new generation that emerged in the 1990s. But he is ambivalent about the benefits of EU membership. "Why shouldn't rural Ireland say no to Nice?" he demanded. "What has it done for them? All the investment is concentrated in Dublin and the other cities.

"The village I come from in the west of Ireland has become a ghost town in the past 10 years. The EU hasn't stopped the decline. When the government warns us that the gravy train could halt, a lot of people shrug their shoulders, look around and wonder if it ever really arrived in the first place."