Like a giant waking from a long slumber, Germany takes over the leadership of the European Union next month just when its politicians and businessmen are at last feeling more confident. The economic growth rate has picked up sharply, reflecting some of the essential, though not spectacular, reforms introduced over the past two years. The grand coalition, led by Angela Merkel, the Christian Democratic Chancellor, has proved more capable than many Germans expected when it took office, though its popularity has fallen back considerably since the heady days of the World Cup. And Germany’s unions and voters appear finally to have understood that without a robust economy, underpinned by realistic social policies, Germany will be unable to exercise its full and due weight in Europe.

The EU needs a presidency that is not afraid to tackle the big issues head-on. The Finns, diligent and conscientious, have done a good job for the past six months, but the coming Helsinki summit is unlikely to achieve much progress on the pressing issues: energy security, internal markets, the effects of an ageing population, migration and the integration of minorities. And on one external challenge there has been a complete breakdown: the stalemate over Turkish accession after the EU Commission’s decision to suspend eight of the negotiating chapters.

The Turkish “train crash” comes at the worst possible time for Germany. There had been hopes that the talks would be moving forward slowly, conducted by officials with little need for Berlin’s input. But now the coalition will have to take political initiatives on one of the issues that divides the Social Democrats fundamentally from their CDU partners in government. That will either widen the splits in a fragile coalition or force Mrs Merkel to argue the cause of Turkish membership that she herself opposes.

German leadership of the EU will also be squandered if, as expected, Berlin decides to make the revival of the mothballed European constitution the centrepiece of its presidency. Germany’s ambassadors have been summoned back to Berlin recently to be told that, after a period of “listening” to ideas from the other 24 member states, Germany will be looking for ways to revive as much of the package as possible, despite the rejections of both France and the Netherlands. Arguing that the 18 countries that have ratified would expect no less, Berlin has rejected cherry-picking those elements in the package that are less contentious and necessary for the smoother functioning of an enlarged union. It even appears to calculate that with lame-duck governments in many EU countries, Berlin can rescue a large part of the full text by adroit political manoeuvring.

This is a significant mistake, sure to be opposed by Britain and other states who see the constitution now as an irrelevance. Of far more importance is the sustaining and boosting of growth, in Germany and in the EU, the further liberalisation of the markets, renewed efforts to ensure energy security and a rebalancing of the EU’s troubled relationship with Russia. German economic strength is essential to European prosperity and vice-versa. If the coalition sets out to pursue this goal, it will mark a valuable presidency; if instead it is distracted by a constitutional chimera, it will leave behind only shadows.