David Cameron wants his own way within the European Union. Alas for him, other leaders might call his bluff

The Prime Minister needs allies and he has 15 months to find them

The scale of David Cameron’s ambition is rarely recognised. The Prime Minister intends, if he wins the next election, to renegotiate the treaties of the European Union. He wants to remove the aspiration to an “ever closer union” among the peoples of Europe; to restrict the “free movement of workers”, which is another founding principle of the union; and to restore to the UK Parliament – which at that point may no longer include MPs from Scotland – unspecified powers from Brussels.

Agree with those alterations or not, Mr Cameron does not lack bravery. This was made clear by François Hollande, the French President, at his joint news conference with the Prime Minister yesterday. “Revising the treaty is not a priority,” said Mr Hollande. This was French for: “You’ve got to be joking.”

The only government in the EU that has any interest in rewriting treaties is Germany’s. Angela Merkel would like to rewrite the rules governing the eurozone and its relations with non-eurozone EU members, but in recent months has gone rather quiet about it, because she realises that the chances of agreement lie somewhere on a scale between Never Land and impossible. Treaty revisions require approval by governments of all 28 member countries and in several cases by referendum as well.

The last time the treaty revision circus began, it was for the federalist project of drawing up a “constitution” for the EU – a project heading in the opposite direction to that of Mr Cameron’s anti-federalism. The constitution absorbed years of political energy and finally collapsed when it was rejected by referendums in France and the Netherlands. Even then, it staggered on for years more, in the form of the limited changes of the Lisbon Treaty. The appetite for going through all that again, in reverse, is limited, except in the UK and possibly the Netherlands.

Mr Cameron needs allies and he has another 15 months to find them. Yesterday, he found only unhelpful obstruction. EU renegotiation is “a question for both of us”, said Mr Hollande, pointedly. “I won’t say if it’s realistic or not.” One does not need to be a linguist or a diplomat to translate that one.

The Conservative Party leader’s plan is that, with the mandate of the British electorate in his sails, and with the threat of a UK referendum in 2017 ahead of him, the reluctant ships in the EU convoy will be harried into line. Faced with the prospect of the UK leaving the union, he calculates, Mr Hollande and the Anglosceptics will start to negotiate terms.

As we say, it is an ambitious approach to European diplomacy. The usual approach in the EU is for leaders to swear undying loyalty to the European dream in public and to pursue their national interest with brutal cynicism in private. Mr Cameron’s strategy is a high-risk one. He protested again yesterday that he wants to renegotiate the terms of UK membership so that we can stay in the EU. But if the threat of the UK’s exit is real, as it must be to carry any weight, he risks having his bluff called.

Mr Cameron has many good ideas about reforming the EU, and he does have the public support of Ms Merkel and, sometimes and on some questions, other leaders. But as was proved yesterday, he does not have enough powerful allies in Europe to ensure that his ambitions have a good chance of being realised.