Number 10 has denied reports that Gordon Brown has asked senior officials to lobby in Europe for Tony Blair to become its new president.
The Guardian reported that Brown's most senior adviser on Europe, John Cunliffe, and Britain's European Union ambassador Kim Darroch were "taking soundings at senior levels".
Downing Street dismissed the report as "speculation" as pressure grows on Blair to publicly declare he will stand for the post.
The position will be created once the Lisbon Treaty is ratified, with only the Czech Republic yet to sign up. The country's Eurosceptic president, Vaclav Klaus, has already conceded defeat and is expected to sign the treaty shortly.
An increasing number of senior Labour figures have declared their support for Blair to become the first EU president.
The Foreign Secretary, David Miliband, said on Monday that the EU needed the former prime minister's "strong, persuasive voice".
He told the BBC: "This is a time when a strong European voice is more needed than ever, it's not a time for shy retiring violets... Europe needs a strong, persuasive, articulate advocate."
The Europe minister, Chris Bryant, added his support last night. He said: "We need a far more effective Europe on a global stage and if you want that then you probably want somebody like Tony Blair because they would be able, quite simply, to make a far more effective case around the world."
But the Conservatives' Europe spokesman, Mark Francois, said Blair was the wrong person to lead the EU.
He said: "Tony Blair was forced out of office in this country by his own party, and now we have Labour politicians desperately running around saying he should get this job."
EU leaders will discuss possible candidates for the presidency in secret at a Brussels summit on Thursday. They will also agree the remit of the new president, something which is likely to determine whether or not Blair stands.
