Gordon Brown is expected to hold last-minute talks with Tony Blair and Nicolas Sarkozy, the French President, tomorrow to plot how to avoid a referendum on the future of the European Union.

The key discussion, before this week’s summit of European leaders in Brussels, will centre around Britain and France’s plans to fight off efforts to revive an EU constitution. They are likely to be connected by video conference, The Times understands, after Mr Sarkozy’s diary was thrown into confusion by the unexpected surge in support for the opposition Socialists in last night’s French parliamentary election. Both countries are committed to talks because they are desperate to block moves for a referendum on an EU Treaty.

On Friday Downing Street appeared to rule out in advance the question of whether a new treaty would be put to a vote, insisting that there was an “emerging consensus” that it would be an “amending treaty”, rather than a new constitution. No 10 added that there was no precedent for holding a referendum on a treaty that only amended previous agreements. Mr Blair’s promise in 2004 for a referendum was only for a new EU constitution, a government spokesman said. Mr Brown’s allies, however, say that a referendum may still be held if it becomes clear that the summit treaty is the old EU constitution in all but name.

They endorsed comments made by Geoff Hoon, the Europe Minister, who said that the final judgment on whether it needed to be put to a referendum had to wait until the “outcome of negotiations”.

Mr Hoon, speaking yesterday on The World This Weekend on BBC Radio 4, said: “Clearly a judgment has got to be made in terms of what is in the final package. It is important not to judge the outcome of the negotiations, but equally we are trying to negotiate an amending treaty.”

There were signs yesterday that Mr Blair will attempt to do a deal on the EU charter of fundamental rights, one of the most controversial aspects of the proposed treaty, by negotiating opt-outs from parts that cross British “red lines”. These include anything that gives the EU enhanced powers to set social or employment law, or overrule British common law.

Mr Sarkozy is under less pressure than Mr Blair and Mr Brown to hold a referendum on the outcome of the talks. During the presidential campaign he made it clear that he would regard victory as a mandate to negotiate a treaty that required only parliamentary approval and not a repeat of the popular vote lost in France in 2005.

Among the topics sure to be discussed between Mr Blair, Mr Brown and Mr Sarkozy is the French President’s reported suggestion that Mr Blair be the first full-time president of the EU Council, a post envisaged in the new treaty.

Downing Street played down the idea and yesterday Margaret Beckett, the Foreign Secretary, said that she thought it “singularly unlikely”. Mr Hoon, however, said he thought that Mr Blair would be a strong candidate.

The idea met with amusement from European diplomats yesterday because Britain was the first country to propose a full-time EU Council president back in 2002. “His name has been put into the basket many times over the past couple of years,” one diplomat told The Times. “But we are far from selecting a candidate, let alone the incumbent.” Other possibilities include Bertie Ahern, the Irish Prime Minister, and Guy Verhofstadt, ousted by voters last week as Prime Minister of Belgium.

Angela Merkel, the German Chancellor, who is trying to gain support for a redrafted EU constitution, could be a candidate if her fragile coalition government collapses in the next year. She continued her round of diplomacy before the summit, meeting Mirek Topolánek, the Prime Minister of the Czech Republic, in Berlin at the weekend.

Times Recommends

• The bright side of this winter rain
• Story behind the picture: Snow Leopard, 2008
• Times Charity Appeal: The Place2Be