Leading Article: The PM must stop justifying the treaty and start to sell it

Gordon Brown faces a battle when he presents the results of the Lisbon summit to Parliament today. There is little doubt the Government will have a majority behind it over the Reform Treaty, for there are not enough Labour mavericks and doubters among the Liberal Democrats for it to be any serious danger here.

The danger is rather that Mr Brown will fail to put the business of a referendum on the European treaty behind him – to achieve "closure" on the issue – and that the Tory campaign for a vote will not lose momentum. Having closed ranks in demanding a referendum, the Tories can hardly be expected to back down now.

The wrong way for the Prime Minister to go about this – though a tempting one, perhaps – is to pursue a negative-sounding narrative about what the Lisbon treaty is not, boasting about Britain's success in drawing red lines around this and opts-out from that.

But by fighting his corner in this manner, and by drawing on the anti-European lexicon of the Tories, Mr Brown may only be throwing petrol on the flames of Eurosceptic opinion. Inadvertently feeding suspicions that the Government has caved in to an intrinsically undesirable political deal, he may simply encourage the anti-European camp to uncover evidence that the famous red lines are more blurred than we understand. This will probably not prove very difficult to do in the coming weeks and months; some of the concessions that Britain claims to have secured are vulnerable to different interpretations. Others may come with a price tag.

If Mr Brown wants to put the Reform Treaty behind him, he would do better to place less emphasis on red lines and start trumpeting the Lisbon deal as the long-awaited fresh start that almost the whole of the rest of Europe believes it to be.

He might point out the absurdity of Britain, the consistent champion of European Union enlargement, appearing squeamishly opposed to a treaty whose primary aim is not the concentration of new powers in Brussels but the establishment of basic mechanisms, enabling a community of 27 countries to live and work together in a reasonably harmonious fashion.

An argument on those lines would put the Tories on the back foot because they championed the inclusion of the former Eastern bloc nations into the EU as much as anyone. Why not ask them how they expect the enlarged EU, which they helped bring about, to work? Why not ask them also who their remaining allies are? Not long ago, the Tories were claiming that the Poles and Czechs shared their own profoundly sceptical vision of Europe, and that only "old" Europe was stuck in a groove. Now the Poles have won their battle over their level of representation in the Commission, they seem to have gone quiet, and we hear no more from the Tories about their new Eastern European soul-mates.

The Government needs to call the Tories' bluff over Europe and stop playing the game by their own Eurosceptic rules, however difficult this may be for Mr Brown personally, oscillating as he appears to do, between Europhile and Eurosceptic positions.

He has promised to articulate a "vision" of the world rather than a set of improvised policies. Europe is one place to start. When it comes to the great challenges we face – terrorism, the environment and globalisation – it is surely obvious to most people that we can only hope to address and overcome them jointly as Europeans rather than as individual states.

If Mr Brown had the courage to spell that out unambiguously, he would probably win the respect and approval of most of the country for doing so, as well as putting the debate over the Lisbon treaty to rest.