Irish PM Brian Cowen said he respected the vote but it had caused a "difficult situation" that had "no quick fix". Leaders of the No campaign said the vote was a "great result for Ireland". An earlier, more wide-ranging EU draft Constitution failed after French and Dutch voters rejected it in 2005.

'Uncharted territory'
The Irish No campaign won by 862,415 votes to 752,451. Turnout was 53.1%. Mr Cowen said: "The government accepts and respects the verdict of the Irish people." He said he would work with other EU leaders to try to find an "agreed way forward" but that the bloc was in "uncharted territory". "Ireland has no wish to halt the progress" of the EU, he said. A referendum was mandatory in Ireland as the country would need to change its Constitution to accommodate the treaty.
European Commission President Jose Manuel Barroso said he had spoken to Mr Cowen and agreed with him that this was not a vote against the EU. "Ireland remains committed to a strong Europe," he said. "Ratifications should continue to take their course."
France and Germany quickly issued a joint statement expressing regret over the Irish result. British Foreign Secretary David Miliband said the UK would press on with ratification, saying: "It's right that we continue with our own process." Spain has said a solution will be found but Czech President Vaclav Klaus said ratification could not now continue.
Mr Barroso said EU leaders would have to decide at a summit next week how to proceed. He called for the EU to continue focusing on issues of interest to people like jobs and inflation, energy security and climate change.
But BBC Europe editor, Mark Mardell, says this is a multiple crisis for the EU - a crisis of rule change, of legitimacy and of morale. In the end, he says, the Lisbon treaty could be declared dead: some parts of it would be implemented without a treaty, others abandoned, others put in a new treaty when Croatia joins the EU in a couple of years time.
Declan Ganley of the anti-treaty lobby group Libertas said: "It is a great day for Irish democracy." He added: "This is democracy in action... and Europe needs to listen to the voice of the people." The No campaign was a broad coalition ranging from Libertas to Sinn Fein, the only party in parliament to oppose the treaty. Gerry Adams, the president of Sinn Fein, said: "People feel secure at the heart of Europe, but they want to ensure there's maximum democratic power."

Confusion
Correspondents say many voters did not understand the treaty despite a high-profile campaign led by Mr Cowen, which had the support of most of the country's main parties. Mr Cowen accused the No camp of "misrepresentation", saying voters had voiced concern about "issues that clearly weren't in the treaty at all", the Irish Times reported.
The treaty, which is designed to help the EU cope with its expansion into eastern Europe, provides for a streamlining of the European Commission, the removal of the national veto in more policy areas, a new president of the European Council and a strengthened foreign affairs post.
The treaty was due to come into force on 1 January 2009. Fourteen countries out of the 27 have completed ratification so far. Just over three million Irish voters are registered - in a European Union of 490 million people.
Source : BBC News