Blair fires the first shot in a long campaign for referendum victory

Tony Blair came out fighting for the European Union constitution yesterday but ducked a challenge by Eurosceptics to put it to an immediate referendum. The vote is expected to be delayed until 2006.

The Prime Minister put his faith in a long campaign to expose what he called "the myths" about the new EU blueprint, insisting that Britain would retain control of its tax, foreign, defence, asylum and industrial relations policies. But he admitted: "It is going to be a tough battle."

Mr Blair said Parliament would debate the EU treaty before the general election, expected in May next year, but a referendum would not be held until afterwards. Ministers said it would be "difficult" to hold a plebiscite in the second half of next year because Britain will hold the EU's rotating presidency, and early 2006 has been pencilled in as the likely date.

Robert Kilroy-Silk, the UK Independence Party MEP, likened Mr Blair to Neville Chamberlain and his appeasement of Hitler. He told the BBC: "He's waving a piece of paper saying, it's OK, I've only given a little bit away of our sovereignty."

Michael Howard, the Tory leader, will accuse the Prime Minister of "running scared" when he reports to the Commons todayon the EU summit in Brussels which approved the constitution. The Tories and UKIP said yesterday there was no reason why the referendum could not be held this year.

Mr Blair told the BBC's Breakfast with Frost programme that the Tories and UKIP feared that the longer the debate went on, the more likely it was that the truth about the constitution would emerge. "It will be a battle between reality and myth," he said.

He added: "We have won every single thing we wanted to secure. This treaty gives us the chance to play a vital part in decision-making at the heart of the EU while it protects completely our right to set our taxes, run our foreign policy and defence and do the things that people want us to do." He confirmed that he had made a concession that would allow other EU states to forge ahead with integration, including a common tax policy, without Britain.

Mr Blair took comfort from apparently hostile opinion polls published yesterday, arguing that people would support the constitution when they knew that Britain would keep control of its key policies.

An ICM poll, for the cross-party Vote No campaign, showed 57 per cent would reject the constitution if a referendum were held tomorrow. A YouGov poll showed voters would vote "no" by 49 per cent to 23 per cent. But it also revealed widespread ignorance about the constitution and suggested that if myths about its implications were exploded a majority would back it.

Yesterday a string of senior ministers defendedthe constitution. Jack Straw, the Foreign Secretary, said it would "end any speculation, any possibility of the EU becoming a federal superstate". He told BBC Radio 4 that a referendum could be won, adding it would be "quite a long time" before it was held.

Andrew Smith, the Work and Pensions Secretary, said on BBC1's Politics Show that he was "absolutely confident" that people would endorse it.

But the Prime Minister came under pressure from both factions of the Europe divide in his own party. Keith Vaz, the former Europe minister, warned that the referendum would be lost unless the Government did more to promote the constitution. He said: "We have nothing to fear from this constitution. It is going to make Europe more modern, more democratic. But what needs to happen is that we need to make that clear to the British people. At the moment that argument is not getting across because there is simply no campaign out there among the public."

Today Labour Eurosceptics will relaunch a group called Labour Against a Superstate, which could win the support of 40 Labour backbenchers who oppose the constitution. Frank Field, the former social security minister, warned that the issue could cost Mr Blair his premiership and said it would be better to have the referendum before the election.

He said: "My view is that people are so upset by Mr Blair's behaviour that they actually want to get even with him in a very significant way. Better to get even with him over the European constitution than to get even in a general election."