The opposition party's new leader, Jeremy Corbyn, opposes atomic weapons, and had said the issue would be debated at the party's annual conference, which opened today.
But after Labour-supporting trade unions said they would vote to keep nuclear weapons and protect thousands of defence jobs, delegates dropped the issue from the conference agenda.
It's a setback for left-winger Corbyn, who wants the party to consider policies long considered off the political agenda, from nationalising industry to diverging on foreign policy from the US.
He said earlier today that Britain should get rid of its "weapon of mass destruction" and scrap the Trident nuclear program.
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News that Trident would be debated at the conference for the first time in many years had been hailed as a victory by anti-nuclear activists -- but caused despair for Labour centrists, who fear the party faces electoral oblivion under Corbyn.
John McTernan, a former aide to Prime Minister Tony Blair, argued that nuclear weapons are "deeply and broadly supported" by British voters.
A vote to get rid of Trident would also have opened a rift between Corbyn and many Labour lawmakers, who support retaining nuclear weapons. Parliament is due to decide next year how to replace the ageing Trident system.
The divide between pro- and anti-nuclear forces has long been a fault-line in the Labour Party. It was Prime Minister Clement Attlee's Labour government that developed atomic weapons in the years following World War II, making Britain the world's third nuclear-armed state after the United States and the Soviet Union.