Britain is backing Anders Fogh Rasmussen, the Danish Prime Minister, to succeed Romano Prodi as president of the European Commission this autumn but the move faces opposition from France.
Tony Blair will not make his preference for the post public, but will lobby for Mr Rasmussen in the run-up to the summit of European Union leaders in Brussels next month, which is due to choose Mr Prodi's successor.
But France looks certain to oppose the post going to Denmark, which is outside the single currency and backed the US-led war in Iraq. Jacques Chirac, the French President, is pressing the case for Guy Verhofstadt, the Belgian Prime Minister. However Mr Verhofstadt is seen as too "federalist" by Britain. Mr Blair is also anxious to block Germany's favoured contender, the Luxembourg Prime Minister, Jean-Claude Juncker, who is tipped by many to emerge as an eleventh-hour candidate.
Mr Rasmussen, who leads the Danish Venstre (liberal) party, won plaudits for his country's efficient presidency of the EU in 2002. But he upset M. Chirac, by backing Britain and the US over Iraq. Relations have improved since then, though not enough to overcome all French objections.
However three EU leaders, in addition to Mr Blair, are said to have told Mr Rasmussen that they would back him.
Britain is not making the case for Chris Patten, the former Conservative Party chairman who is due to stand down as a European Commissioner this autumn. Sources say he could have emerged as a last-minute compromise next month if EU leaders were deadlocked, but that was unlikely once his name emerged last month and ran into opposition from Paris and Berlin. Yesterday Mr Patten again said he is "not a candidate" for the post.
Another possible candidate, the Irish premier, Bertie Ahern, who holds the EU's rotating chairmanship, also ruled himself out yesterday. However such declarations from politicians are not being taken at face value. Genuine contenders do not want to be exposed as front-runners at this early stage.
Other possible candidates include Pat Cox, who is standing down as president of the European Parliament; Javier Solana, the EU's foreign affairs supremo; Portugal's European Commissioner, Antonio Vitorino; Germany's Commissioner, Günther Verheughen; the former Greek premier, Costas Simitis; the former Finnish prime minister, Paavo Lipponen, and the Austrian Chancellor, Wolfgang Schüssel.
The lack of consensus on who should succeed Mr Prodi is delaying a decision on Britain's choice of its representative on the Commission.