Ireland Shoots Down Plan for a More Unified E.U.

European analysts said it is unclear what will happen now. Many said Brussels had no "Plan B," because the Lisbon Treaty was already a Plan B. It was essentially a modified version of a proposed European constitution that was rejected in referendums in France and the Netherlands in 2005, then withdrawn.

"This is the worst-nightmare scenario, what everyone was trying to avoid," said O'Donnell. "We don't know the next step. People are depressed and wondering what to do."

O'Donnell said there will be "minimal impact on the daily lives of citizens" because of the rejection. She and others said the E.U. will continue operating with its current rules, which they called increasingly inadequate to run a union that has added 12 new member countries in the past four years.

In her view, it is possible that the other member countries will finish ratifying the treaty, then figure out how to deal with the Ireland problem. When Irish voters rejected a treaty regarding E.U. expansion in 2001, officials simply scheduled another referendum the following year, when voters adopted the treaty.

A second possibility is that the E.U. will declare the treaty dead and start over. Future changes might have to be done step by step, rather than in one document, she said.

The treaty would have created a full-time E.U. president and a more powerful foreign minister to represent the bloc with a strong and consistent voice. It would have streamlined the legislative process and given member nations more of a say in proposing legislation.

Critics, including the Sinn Fein political party, argued that the treaty would have undermined Ireland's traditional neutrality, reduced its influence at the European Commission, the bloc's executive arm, and forced it to eliminate corporate tax incentives that attracted huge foreign investment. Supporters said those arguments were simply false.

In the end, many voters seemed confused by all the back and forth. In interviews, many said they rejected the nearly 300-page document because they didn't understand it. It contained no easily understood objective and was a collection of technical changes to a vast bureaucracy.

"I voted no because I don't have a clue what's in it," said Bernie Kiernan, 48, an elder-care worker, who also echoed one of the No campaign's slogans: "If you don't know, vote no."

"If it's not broken, don't fix it. I think I speak for a lot of Ireland when I say that," said John Ormston, 38, manager at the Locke Bar in Limerick. "The government made us feel obliged we had to do it. They said we should say yes, even though they didn't explain things."

Some Irish voters seemed to be not voting on the treaty at all, but rather using the treaty as a way to punish the Irish government. One of the treaty's key backers was former prime minister Bertie Ahern, who stepped down last month amid a government investigation into his personal finances.

"There's a lot of corruption, I think the country is getting a bit out of control," said Claudia Kelly, 29, who said she voted no. "Instead of this, I think we should just concentrate on our own country."

Special correspondent Karla Adam in London contributed to this report.