Pressure for a UK vote
Let us presume, as seems likely, that the Czechs ratify the Lisbon Treaty sooner rather than later. That is what the Czech President Vaclav Klaus hinted to the BBC on Saturday. Lisbon will then be a done deal. At that moment the Tory leadership will have to answer the difficult question "what next?"
David Cameron could come out and say "we'll have to live with it" - and alienate sections of his party. Or he could bow to the fact that there is a strong instinct within Tory ranks for the British people to be consulted in some form or other. And that's when the difficulties start.
Let us say that, within the leadership, the argument prevails that even though the treaty has been ratified there should still be a referendum. Even if Britain voted No it would have little immediate impact. The Lisbon Treaty could not be amended or revoked except by another treaty. It has taken 10 years of argument to get to this point. Imagine how hard it would be to persuade 26 other countries to reopen the whole process.
Then there is the political calculation. As I have said before, would David Cameron, wrestling with a ballooning budget deficit and his plans to rebuild "broken Britain", want a massive row with the European Union? It would hoover up huge amounts of energy and political capital. Some may argue it would be good politics. The British people would thank him. But here is a curious fact. When people are asked at election time what are the key issues that determine how they vote, Europe usually ranks around 10th. It would be a bold political gamble to believe that a drawn-out dispute with much of Europe would reap significant political dividends.
Then there is the role of the business community and the City. I have no idea which side they would back in a referendum. They may well divide with the rest of the nation. But would they support the uncertainty of trying to renegotiate a treaty in the face of determined opposition?
But say David Cameron shies away from a referendum but offers instead a vote on redefining our relationship with Brussels. Firstly, it would be a difficult question to frame.
The party could decide that it wanted to opt out of employment or social policy. The attraction for the Tory leadership would be that, if successful, they would have returned some powers to Westminster. It might even satisfy some convinced Eurosceptics. It is not clear, however, why Britain would need a vote. The government could simply begin the renegotiation process. It might feel that a popular mandate would strengthen its hand, but as the former Foreign Secretary Malcolm Rifkind said today, such a vote would have the force of an opinion poll. It could not really be a referendum.
So the dilemma for the Tory leader is this: how do you satisfy the yearning, particularly within his own party, for the British people to have a say, without opening up old divisions and without creating a long-running crisis?