Politicians who supported the No side in the Nice referendum have predicted that the issues at the heart of the Treaty would come back to haunt the Republic.
The Sinn Féin leader, Mr Gerry Adams, said while he welcomed that fact that there was such good debate during the campaign, he warned that the issues of neutrality, sovereignty and a two-tier Europe would not go away.
"All of these should be a matter of concern and will still be an issue in the years ahead," the Sinn Féin leader told The Irish Times. He said the Yes campaign managed to exploit the generosity of the electorate by appealing to voters to go with the referendum.
He said it was wrong of the Yes side to suggest that the No side was against European enlargement. "We are for enlargement, but it is the others issues such as neutrality and a two-tier Europe that were the worries."
While he wished the result had been different, there was good, open debate during the campaign, and everyone who came out to vote should be commended.
He said the fact that less than 50 per cent of the electorate voted should be a concern for the Government and to all people in politics.
Sinn Féin TD Mr Caoimhghín Ó Caoláin described the extent of the No vote as an "excellent turnout against all the odds".
He said the Yes side mobilised the conservative political parties, the leaderships of the Irish Congress of Trade Unions, the Irish Farmers Association, the Irish Business and Employers Confederation and a range of State agencies.
"They spent massive amounts of money in comparison to the No side. The entire political establishment threw their weight into the effort and used dire threats of economic ruin and international isolation. Despite this, 37 per cent of voters refused to ratify the Treaty of Nice."
The result, he added, was disappointing and a setback for sovereignty and neutrality and for the accountability of institutions within the European Union.
"Unlike the Government and its allies who dismissed the people's verdict on the last occasion, we accept it, but we will maintain continued vigilance against the growing inequality within the EU, a process Nice will accelerate."
The leader of the Green Party, Mr Trevor Sargent, said the result was not unexpected given the size of the resources put into the Yes vote. "I think the context of the second referendum meant that people were less confident."
Mr Sargent said the economic difficulties and the announcement of 1,000 job losses around the State in the last week made people vulnerable to threats of what could happen if they voted No.
He said fear played a large part in this campaign. He welcomed the fact that the turnout was higher than in the last vote and that there was a greater level of engagement by civil society as well as politicians and the media.
He was philosophical about the result and had no difficulty accepting the will of the people, but he was "sad" that the first referendum was not taken as a legitimate outcome.
Socialist Party TD Mr Joe Higgins said the Yes campaign was successful due to the "overwhelming weight of Yes propaganda in the press" and the huge disparity in spending by the Yes side. He also said that fears about marginalisation and flight of investment in the event of a No vote helped the Yes said.
He said some of the key issues raised during the Nice Treaty campaign would continue to be controversial, such as the thrust towards providing the EU with a military wing, and an integrated armaments industry.
Mr Higgins said the question of lessening the democratic control over the institutions of the EU would also be challenged.
He said the Socialist Party would continue to campaign for a Europe for working people, with the wealth and resources under democratic ownership, with control of the armaments industry disbanded and resources geared to resolving the real problems of humanity.