Conservatives will stage a referendum on whether Britain should remain a member of the European Union by the end of 2017 if they win the next election, David Cameron will promise on Wednesday.
The Prime Minister will for the first time declare himself in favour of an in/out referendum, but will say it should not happen until the future shape of the 27-nation bloc is clear.
And he will make clear that he will campaign for continued membership of a "more flexible, adaptable and open" EU.
During a speech in London, Mr Cameron will say that the Conservative manifesto for the 2015 general election will ask for a mandate to negotiate a "new settlement" for Britain in Europe. Enabling legislation would be drafted before the election and passed by the end of 2015 to complete the renegotiation and then submit it to voters in a referendum within the first half of the next five-year Parliament.
Mr Cameron will say: "It is time for the British people to have their say. It is time to settle this European question in British politics. I say to the British people: this will be your decision. And when that choice comes, you will have an important choice to make about our country's destiny."
Mr Cameron was initially planning to make his speech in the Netherlands last Friday, but had to postpone it in order to focus on the Algerian hostage crisis. More than six months in the planning, the address has been so often delayed that the PM joked he was taking a "tantric" approach to policy. It comes amid growing Tory backbench concern about the rising tide of support the UK Independence Party, which has recorded poll ratings of 10% or more with its call for an immediate in/out poll.
Mr Cameron will acknowledge that "public disillusionment with the EU is at an all-time high" and will describe democratic consent for the EU within the UK as "wafer-thin". But he will argue that a vote now between the European status quo and departure would be "an entirely false choice", as the EU is set to be "transformed perhaps beyond recognition" over the coming years by the measures needed to save the single currency.
He will say: "We need to allow some time for that to happen - and help to shape the future of the European Union, so that when the choice comes it will be a real one."
Mr Cameron will set out what he terms "a positive vision for the future of the European Union, a future in which Britain wants - and should want - to play a committed and active part". The five key principles underpinning the future EU should be competitiveness, flexibility, power flowing back to member states, democratic fairness and accountability, he will say.
And he will warn that, if these issues are not addressed, "the danger is that Europe will fail and the British people will drift towards the exit". Mr Cameron will declare: "I do not want that to happen. I want the European Union to be a success. And I want a relationship between Britain and the EU that keeps us in it."
UK 
