Prominent Labour figures, including a former defence minister speaking yesterday, have denounced the project.

The Prime Minister will promise MPs that they will be able to vote on it in March. However, if the rebellion is strong enough, he could end up dependent on the support of the Conservatives, who say that they support buying a new nuclear deterrent in principle.

A survey of MPs by CommunicateResearch for The Independent found that 50 per cent of Labour members wanted to retain the deterrent as against 39 per cent who did not.

Mr Blair will confront his critics by making a statement in the Commons outlining the case for a new generation of nuclear ballistic-missile submarines to carry an enhanced version of the US Trident deterrent, which will remain in service until the 2040s.

The details of the proposals will be published beforehand in a White Paper, to be rubber-stamped by a Cabinet meeting this morning. The decision to stick with the submarine-launched deterrent system will safeguard up to 15,000 jobs and could cost the taxpayer in the region of £20 billion.

The White Paper will put forward all the arguments for retaining a nuclear deterrent, emphasising the importance of ensuring stability in a future when dwindling oil and gas supplies could lead to confrontation. It would also serve as insurance policy against terrorists acquiring a nuclear capability, the Government is expected to say.

The left-wing leadership candidate, John McDonnell, and a deputy leadership candidate, Jon Cruddas, are making their opposition central to their election campaigns. Peter Kilfoyle, a former defence minister, told the BBC yesterday: “It is a very inopportune moment to be replacing Trident.”

The Archbishop of Canterbury, Dr Rowan Williams, is expected today to attack the plans to replace the deterrent. He is also preparing a new year statement exploring the morality of nuclear weapons that will reflect the concerns of 19 bishops who warned Mr Blair in July that the possession of Trident was “evil”.

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