Ireland's voters have rejected the European Union reform treaty, a blueprint for modernizing the 27-nation bloc that cannot become law without Irish approval, electoral officials said Friday. In a major blow to the EU, 53.4 percent of Irish voters said no to the treaty. Irish Prime Minister Brian Cowen now will join other EU leaders at a summit next week to try to negotiate a new way forward. Anti-treaty groups from the far left and right mobilized "no" voters by claiming that the treaty would empower EU chiefs in Brussels, Belgium, to force Ireland to change core policies - including its low business tax rates, its military neutrality and its ban on abortion.

"This is a very clear and loud voice that has been sent yet again by citizens of Europe rejecting the anti-democratic nature of Brussels governance," said Declan Ganley, leader of Libertas, the most prominent anti-treaty campaign group in Ireland.

The euro common currency fell to a one-month low on the news.

An EU constitution failed after French and Dutch voters rejected it in 2005. Ireland was the only member that subjected its would-be successor, the Lisbon Treaty, to a national vote. The Irish constitution requires all EU treaties to be ratified by referendum.

Ireland's minister for European affairs, Dick Roche, said the country was constitutionally barred from passing the treaty now. He predicted it would be difficult, if not impossible, for EU leaders to find a solution that would permit a second Irish referendum.

"As far as I'm concerned, this treaty is a dead letter," Roche said, adding that Ireland's voters have "made life very difficult for us going out to Brussels. We are in completely uncharted territory here, a very strange position."

In the EU's power base of Brussels and other European capitals, leaders vowed to complete ratification of the Lisbon Treaty through the governments of the other 26 members - even though, legally, the treaty cannot come into force because of the Irish rejection.

At the major ballot-counting center in Dublin, Finance Minister Brian Lenihan struggled to speak to reporters as anti-treaty activists jubilantly drowned him out with songs and chants of "No!" He eventually gave up and walked out, as one activist waved a sign reading "No to foreign rule" over his head.

Rural and working-class areas were almost universally anti-treaty. Better-off parts of Dublin registered stronger support for the EU. In suburban south Dublin, a largely wealthy and highly educated district, the "yes" camp triumphed with 63 percent of the vote. But a neighboring, scruffier district voted 65 percent "no."

The Lisbon Treaty and the failed constitution before it sought to reshape EU powers and institutions in line with the bloc's rapid growth in size and population since 2004.

Both documents proposed to strengthen the roles of the EU's president and foreign policy chief, reduce the areas where individual nations could veto policy changes and increase the powers of the European Parliament to scrutinize EU laws.

Ireland views itself as a pro-EU state that has broadly benefited from 35 years of membership. Yet even here, a majority of voters appeared determined to register their opposition to the growth of a continental government that would erode Ireland's sense of independence.

Anti-treaty pressure groups warned that the EU would use treaty powers to reduce Ireland's ability to control its own tax rates and maintain a ban on abortion. Such claims were vociferously rejected by the government and major opposition parties, all of whom campaigned for the treaty's ratification.

"People felt a convincing case for the treaty had not been made, and they felt hectored and bullied into supporting it while the wool was being pulled over their eyes," said Richard Boyd Barrett, leader of a hard-left pressure group called People Before Profit.