A candidate to become Labour's deputy leader has said he is not convinced of the need to replace Britain's ageing nuclear weapons.
The operational end of Trident's life is due to be 2024
Jon Cruddas said he was prepared to use his campaign for the deputy leadership to press for much more consultation on whether Trident should be replaced.
He told GMTV it was a "touchstone issue" for Labour and his "instinct was to be opposed to it".
A white paper outlining options for replacing Trident is due on Monday.
Dagenham MP Mr Cruddas said: "I want to see actually a debate across the party about [Trident] because I think this is so critical and such a profound issue that the party has to be involved."
Mr Cruddas' comments come after former Home Secretary Charles Clarke's said on Thursday he was "extremely sceptical" about the need to replace Trident.
Mr Clarke, the most senior Labour MP to speak out on the issue, said Trident had been designed for the Cold War era.
Prime Minister Tony Blair and Chancellor Gordon Brown have both indicated they want to see the UK keeping its own nuclear weapons system.
Although there have been reports of some disagreements in the Cabinet, ministers are to outline their favoured option - expected to be a replacement for the Trident system - in the white paper.
There will then follow a three-month consultation on the plans and a vote by MPs in the House of Commons.
Jon Cruddas wants the future of Trident to be debated further
Ministers want a quick decision to ensure any replacement is ready when Trident's working life ends in 2024.
Supporters argue Trident is needed to deter any threat - particularly at a time when countries like North Korea and Iran harbour their own nuclear ambitions.
The Conservatives also back retaining nuclear weapons.
Liberal Democrat leader Sir Menzies Campbell believes Britain's nuclear weapons capability should reduced by half, retaining only 100 warheads.
He said a decision on the Trident system should be made after 2014 when a clearer picture of nuclear threats and proliferation was known.
Britain has 16 Trident missiles based on each of the four nuclear submarines.
Anti-nuclear campaigners fear the government has already decided to go ahead with replacing Trident.
Critics have said the cost of replacing Trident - estimated at up to £25bn - would be better spent elsewhere, particularly as nuclear weapons would be useless in the fight against international terrorism.