Four options.
Option 1
FRENCH AND German politicians have raised the prospect that Ireland could either voluntarily leave the union or negotiate a special relationship with the EU to allow the 26 other EU states to proceed with the Lisbon reforms.
They argue that less than one million Irish No-voters cannot negate the wishes of 490 million EU citizens that want the Lisbon reforms.
This is undemocratic, they say, and Ireland should follow a "principle of loyalty", whereby one state does not block other members of the union from proceeding.
Legally this is difficult. Lisbon cannot be implemented by 26 countries as it states all 27 states have to ratify the text before it becomes law. But pro-European think tanks in Brussels have already begun work on an alternative scenario whereby 26 states (not including Ireland) agree to set up a new union in parallel with the EU and implement the Lisbon reforms.
In this nightmare scenario Ireland would have to negotiate a bilateral relationship with the EU institutions - perhaps becoming some sort of associate member or joining Switzerland and Norway in the European Economic Community. This would be extremely difficult given that Ireland has adopted the euro. There are also many unanswered questions about how Ireland could interrelate with the new innovations created by Lisbon such as the European Council president or the new voting system.
Option 2
France and Germany may feel that threatening to exclude Ireland under Option 1 could persuade Taoiseach Brian Cowen to hold another referendum on the treaty with new protocols attached to allay voters' fears. Under this arrangement Mr Cowen could perhaps get explicit guarantees that Lisbon does not undermine Ireland's sovereignty over tax or that it can never lead to conscription of Irish young people into an EU army.
Getting these protocols would be easy as most people who have read the treaty acknowledge that it does not change the position in these areas for Ireland. Yet putting a similar treaty in front of voters a second time is fraught with the risk of an even bigger rejection than Lisbon received.
One big concession that Irish negotiators may be able to extract from Brussels and other EU capitals is to guarantee that each member state has a commissioner. However even this would create problems as all the states that have already ratified Lisbon would have to re-ratify the text again.
Option 3
Mr Cowen could declare the Lisbon treaty dead this week and urge member states to continue using the existing EU treaties and put off institutional reform until the EU can build further popular support.
The EU decision-making process created by the 2003 Nice Treaty is cumbersome in an enlarged union but nevertheless does work reasonably well. For example, seemingly intractable problems such as agreeing to share DNA information among EU police forces have been solved.
Some of the innovations in the Lisbon treaty could be introduced without the need to hold referendums or ratify new treaties. For example, the existing treaties enable EU leaders to decide on the basis of a unanimous vote to remove national vetoes over legislation in the sensitive justice field.
However it is highly possible that if Lisbon dies some existing EU states would decide to go ahead with further integration themselves, creating a two-speed Europe. The existing treaties allow this to be achieved through enhanced co-operation.
Option 4
Mr Cowen could tell EU leaders that Lisbon is a step too far and urge a full renegotiation of the text of the treaty to meet Irish concerns. This could provoke serious bad feeling among the EU diplomats who spent seven years crafting the EU constitution and the Lisbon Treaty. But it would reflect how the French and Dutch responded to their referendum defeats in 2005.
There is little appetite in Europe for the type of lengthy convention and intergovernmental conference which drafted the EU constitution. But it is possible that some of the innovations in Lisbon could be repackaged and presented to governments for ratification along with Croatia's accession treaty, which will have to be approved by all states. Croatia is due to join the EU in 2010.