Launching Labour's Euro election manifesto, Mr Blair insisted there was no need to "put an arbitrary time limit" on British entry, but denied this was a departure from plans to call a referendum after the next general election.
He insisted that Britain had to be in a position to call a referendum early in the next parliament, provided the Government's five economic tests were met.
The Prime Minister denied he was "playing down" the single currency. However, his change of tack was seen as an attempt to limit the damage from William Hague's decision to put the issue at the heart of the Tories' Euro campaign.
Labour strategists fear that Eurosceptic voters will be more likely to turn out on 10 June, boosting the Tories' prospects, and that many Labour supporters will stay at home because they are broadly happy with the Government. But Labour Party workers report hostility to the euro among older voters. "We have become a country of protest votes and this will help the Tories," said one Labour source.
Last night the Tories claimed Mr Blair, who was reported as saying he "loved" the pound before the 1997 general election, had put his plans to scrap sterling on hold for the three-week Euro campaign. "It will be another very short love affair," said a Tory source.
Today Mr Hague will step up his campaign by warning that Britain would "share the pain, not the gain" if it joined the single currency.
Yesterday Mr Blair said: "We believe Britain should be part of a successful single currency. But the test must be our own national economic interest, and we have set out the conditions to meet it. Our intentions are real; our conditions are real."
Mr Blair declared that the Euro elections were "a battle for the long- term future of Britain." He said: "I believe it is time to end - once and for all - our ambivalence to Europe. We can state positively that we need not be fearful."
He insisted that Labour's more positive approach and strong leadership were already getting results for Britain, while a divided Tory Party would leave Britain isolated and impotent on the EU's sidelines.
For the first time, Labour is fighting the Euro elections on a joint manifesto agreed by Europe's 20 socialist and social democratic parties, which was co-authored by Robin Cook, the Foreign Secretary. Mr Blair shrugged off Tory attacks on the manifesto, describing it as a New Labour document. It calls for "increased use of qualified majority voting where desirable.
Mr Blair insisted he would only surrender the veto when this was in Britain's interests, but declined to outline any possible areas.
The manifesto calls for "closer economic co-ordination aimed at ensuring sustainable growth and high levels of employment." It adds: "It is in the interests of all member statesthat the euro is a success."Reuse content