European Union leaders will discuss the bloc’s full-time president and foreign policy chief on Monday when they meet in Berlin to celebrate the 20th anniversary of the fall of the Berlin Wall.

The two top jobs are not officially on the agenda, but diplomats say the topic is expected to dominate the chatter on the margins of a dinner for world leaders hosted by Angela Merkel, the German chancellor.

Herman Van Rompuy, Belgium’s prime minister, is the name on most politicians’ lips for the presidency. But it is far from being a done deal, not least because Nicolas Sarkozy, the French president, has yet to make up his mind. Discussions are continuing among the 27 leaders who will formalise their decision at a summit in Brussels later this month.

Sweden, which holds the rotating presidency, is under growing pressure to reach a decision. “If we had a courageous president we could have settled it this weekend,” a senior European diplomat said. “We know all the names, all the pros and cons.”

David Miliband, UK foreign secretary, has emerged as frontrunner to be EU head of foreign policy.

The two jobs will set the tone for a new era in European public life when the EU’s Lisbon treaty comes into force on December 1.

Some EU officials say the more powerful of the two posts could be that of the foreign policy high representative – a position held for the past 10 years by Spain’s Javier Solana.

The foreign policy chief will not only represent EU governments but will be a vice-president of the European Commission, controlling a multibillion-euro budget and a global staff of 2,000 to 3,000 employees.

By contrast, EU leaders are gravitating towards the view that the first full-time president should concentrate on internal matters, such as preparing the bloc’s summits, of which there are at least four a year.

Mr Van Rompuy, 62, is a Flemish Christian Democrat who reluctantly took the Belgian premiership last December after a judicial scandal brought down his predecessor. The Irish bookmaker Paddy Power rates him as the favourite for the presidency.

Diplomats have said he stands a good chance because he is a likeable, uncontroversial personality from a small, profoundly pro-EU member state. “He’s a new face. He hasn’t had a chance to make enemies,” said one diplomat.

Officials in Paris said Mr Sarkozy would be prepared to accept Mr Van Rompuy if he emerged as the only viable candidate with strong support elsewhere. “He is someone the president respects,” said one official. “And having a francophone in the job is always useful.”

The prospects for Tony Blair, 56, the former UK prime minister, faded last week when he failed to receive much support at an EU summit – even from the Labour government’s nominal Socialist friends in continental Europe.

Peter Mandelson, UK business minister and a close ally of Mr Blair, said it would be “a loss for Europe” to settle for a “low-key” or compromise candidate. “If we keep going for lowest-common denominator, if we keep going for second or third best – because it’s too controversial – in the end, we are all going to be the losers,” he said.

Mr Miliband, 44, tops the list of contenders for the foreign-policy job, partly because some national leaders like his positive, pro-EU perspective, and partly because he comes from the centre-left.

Additional reporting by Joshua Chaffin in Brussels and Bertrand Benoit in Berlin