Following an opinion poll showing that the 'no' vote has overtaken 'yes' ahead of the Irish referendum on Thursday, Europe is bracing itself for a very large spanner in the works.
There is no 'plan B' it is said but that is not actually true. The institutions are still working, legislation is still passing, the EU goes on without the Lisbon Treaty. The status quo is a 'plan B' but that is not good enough.
A 'no' vote matters because it puts a good treaty in jeopardy. It will make the EU more effective, both internally and externally, and more democratic, giving more powers to the European Parliament and domestic parliaments also. Why does this matter? It matters because the EU is critically important in a globalising world to fighting crime and terrorism, reversing the harmful impact of climate change, securing more investment, better managing the economy, creating jobs, and making a telling contribution to international development and global peace and security.
An effective and democratic EU is necessary precisely because of what it enables us to do to protect our national security, prosperity, and promote international peace and development.
Should the Irish say 'no' there are two options. The first option is to carry on with the status quo. It works but not as effectively or democratically as it would do should the Treaty be ratified. This is a possibility but not the best option. The second and better option would be to renegotiate the Treaty as it applies to Ireland and then have another referendum.
There does come a point, however, when the will of a million or so voters in Ireland who would vote 'no' can not drive the agenda of the remainder of the EU and the will of 26 other national Parliaments. So a 'no' vote is messy, Eurosceptics will bray and sneer, but it is by no means the end of the road for a good and necessary Treaty.