As the prime minister prepares to deliver a landmark speech on Europe later this month, the Labour leader accused Cameron of embarking on a gamble by promising to hold a referendum on renegotiated terms of British membership.
Miliband told the Andrew Marr Show on BBC1: "I think it is incredibly dangerous what David Cameron is doing. He is essentially sleepwalking us towards the exit door from the EU."
Miliband rejected out of hand a referendum on the terms likely to be proposed by the prime minister as pro-Europeans intensified their opposition against the No 10 strategy. Lord Mandelson is to join forces with Kenneth Clarke to make the case for whole-hearted British membership of the EU in a new group called Centre for British Influence through Europe.
Lord Heseltine, the former Tory deputy prime minister, warned in the Times on Saturday that the prime minister is taking an "unnecessary gamble". Cameron is expected to say in a speech, due to take place on 22 January in the Netherlands, that the Tory manifesto for the next election will include a pledge to use a major treaty revision to underpin new eurozone governance arrangements to repatriate powers to Britain. The new terms of British membership would then be put to the British people in a referendum after the next general election.
Miliband was scathing about Cameron's tactics. He said: "The last thing we should do is start to say for some date five, six, seven years hence, let's decide now to have an in/out referendum. As Michael Heseltine said very well yesterday, that means you are having a referendum on a negotiation that has not yet begun, with a timescale that is uncertain and an outcome that is unknown.
"That is an incredible gamble. We know why this is happening. He is worried about the threat from Ukip and he is worried about what is happening in his own party. It is the wrong thing to do. It is not in the national interest."
Miliband was asked by James Landale, who was standing in for Andrew Marr as he recovers from a stroke, whether he would rule out a referendum. The Labour leader replied that the coalition has changed the law to ensure that a referendum must be held on any future transfer of powers from the UK to the EU.
But he dismissed the prime minister's plans for a referendum on repatriating powers passed to the EU in the past. "I am very clear. The question for now is should we have a referendum, should we commit to a referendum, should we promise one? I am saying very clearly no is the answer."
Miliband's remarks come after an intense debate in the Labour party about how to respond to the prime minister's speech. The leadership has decided not to rule out a referendum in principle. But it has decided to reject the prime minister's plans for a referendum on as-yet unidentified renegotiated terms of membership on the grounds that this is designed to paper over cracks in the Conservative party.
The intervention by Miliband came amid signs that one of the central elements of the prime minister's plan – a major revision of the Lisbon treaty to underpin new governance arrangements for the EU – may not happen. The Guardian reported on Friday that Angela Merkel, the German chancellor and the only major EU leader calling for treaty revision, has abandoned such plans for the moment. This may change after next year's German elections.
In his interview, Miliband declined to say whether he would restore child benefit for higher rate taxpayers and whether he would restore the 50p top rate of tax. He has criticised the coalition for removing child benefit to higher rate taxpayers and for cutting the top rate of tax to 45p.
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