It has been said that David Cameron does not consider "foreign affairs" to be his strongest suit. We are beginning to understand why. Yesterday, the Tory leader announced he was delivering on his pledge to pull Conservative representatives out of the large centre-right grouping in the European Parliament known as the European People's Party. He also hailed the establishment of an exciting new parliamentary group in Brussels, led by the Tories, called the "Movement for European Reform".

Yet it did not take much probing to realise that what Mr Cameron was actually outlining was rather less substantial. For a start, the Tory withdrawal from the EPP will not take place until 2009. Last December, Mr Cameron said the break with the EPP would happen in "months not years". Now it seems we are back to years. As for the Tories' grand new coalition, it turns out that the only other participant is the little-known Civic Democratic Party of the Czech Republic. And even this hardly counts as a strong partner. We are told that its leader, Mirek Topolanek, was keen to delay the two parties' withdrawal from the EPP because he will need the support of pro-European Czech politicians to form a government. Such weakness is an inauspicious basis for the sort of revolution in European politics that Mr Cameron was talking about yesterday.

The Tories tried to sweeten the pill for those who hoped for immediate withdrawal by pointing out that Conservative MEPs committed themselves at the last European election to remain within the present grouping for the duration of the parliament. But this is disingenuous. The real reason for the delay is that the Tory foreign affairs spokesman, William Hague, failed to persuade any other centre-right parties to leave the EPP along with the Conservatives. Honouring the pledge immediately would have meant asking Conservative MEPs to sit alongside delegates from the UK Independence Party, who Mr Cameron once memorably described as "fruitcakes, loonies and closet racists".

Withdrawal from the EPP was always a foolish pledge. No doubt Mr Cameron, who made the promise in the heat of the Tory leadership election, gave little thought to how it would actually be achieved. The Tory leader has learnt the hard way that serious European parties do not share the Tories' parochial obsessions with "creeping federalism". He has also had a taste of how isolated the Conservatives would be if they fail to work together with the respectable centre-right parties of the continent.

Instead of proceeding with this charade of creating a new European politics, Mr Cameron should admit that he made a misjudgement and get down to work within the present arrangements.