Analysis: Denis Staunton in Brussels finds out how a second No vote would affect plans for enlargement.
Ask any European Union official what will happen if Ireland rejects the Nice Treaty a second time and you will always get the same answer: there is no Plan B. The Commission and most of Ireland's EU partners are confident that Ireland will vote Yes and reluctant to speculate on a defeat.
"Everybody's working on the assumption that the second referendum will result in a Yes vote," according to Mr John Palmer of the European Policy Centre, a Brussels think tank.
The most important question is how a second No vote would affect the EU's plan to admit up to 10 new member-states in 2004. In an interview with The Irish Times last year, the Commission President, Mr Romano Prodi, said the Nice Treaty was not a legal prerequisite for enlargement. "Legally, ratification of the Nice Treaty is not necessary for enlargement. It's without any problem up to 20 members, and those beyond 20 members have only to put in the accession agreement some notes of change, some clause," he said.
Mr Prodi clarified his remarks the following day, stressing that, regardless of the legal position, the treaty was a political necessity.
Many European diplomats agree that technical parts of the treaty such as the re-weighting of votes in the Council of Ministers and representation in the European Parliament could be included in the new member-states' accession treaties. These treaties must be ratified by all 15 member-states and by the applicant countries but they would not require a referendum, even in Ireland.
Prof Alan Dashwood, professor of European law at Cambridge University, suggests that other matters, such as extending qualified majority voting, could be dealt with at the Inter-Governmental Conference (IGC) that will follow the Convention on the Future of Europe.
"If it is politically possible, I can see no legal objection to achieving the aims of the Nice Treaty partly through accession treaties and partly through the treaty that follows the next IGC," he said.
The Amsterdam Treaty envisages the admission of only five new member-states and calls for new arrangements if more are to be admitted.
"At least one year before the membership of the European Union exceeds 20, a conference of representatives of the governments of the member-states shall be convened in order to carry out a comprehensive review of the provisions of the treaties on the composition and functioning of the institutions," it says.
Prof Dashwood believes a generous interpretation of the treaty would accept that the Convention was carrying out a "comprehensive review" of EU institutions. And he believes that any legal challenge to admitting 10 new member-states on the basis of the Amsterdam Treaty would fail.
Mr Palmer agrees that, if Europe's politicians want to proceed with enlargement, the law will be their hand-maiden. But he warns that some member-states could seek to revisit the arguments of Nice before proceeding with enlargement. "It's a set of intricate cross-balances, and you would have to be sure that the thing wouldn't unravel. The risk is enormous," he said.
Although a second No vote is unlikely to derail the enlargement process, Mr Palmer believes it could delay the process. And he suggests that any further delay could reduce support for EU membership in the candidate countries.
"Nothing could be done that wouldn't involve a real delay. Enlargement is irreversible. What is not irreversible is the timetable," he said.
The consequences of a second rejection of Nice for Ireland's position in the EU are difficult to calculate, although there is no question of Ireland being expelled from the EU for voting against a treaty. The Government warns that voting No would make life difficult for the Minister for Agriculture, Mr Walsh, during negotiations over the reform of the Common Agricultural Policy.
On questions involving large sums of money, however, EU member-states tend to act strictly in accordance with their national interests.
Germany, which pays for much of the EU's agriculture budget, will push for sweeping reforms, and France, which benefits most from the subsidies, will resist change.
However, Ireland could suffer in less high-profile negotiations, where goodwill can be crucial to the formation of alliances.