Jeremy Corbyn will "lose massively" in 2020 if he fights the general election on a platform of unilateral nuclear disarmament, a former Labour director of communications has warned.
Writing for The Huffington Post on Thursday, Lance Price, who worked for Tony Blair in the late 1990s and early 2000s, said abandoning a commitment to Trident would be a "suicide mission".
"Labour would lose seats on an industrial scale. Any hope of winning in 2025 would evaporate. The Tories would be in until 2030 if not longer," he said.
Price, who himself is opposed to the renewal of Trident, said a Labour government that had to commit to nuclear weapons was "infinitely preferable" to the "crushing if valiant defeat" that would happen if it went into an election advocating disarmament.
And he said it was wrong of some in the party to equate opposing Trident to being in favour of Corbyn. "If you're genuinely interested in what best defends our nation, rather than simply what's morally defensible, you can and should be both anti-Trident and anti-Corbyn," he said.
"Trident has become a binary issue that defines whether you support Jeremy Corbyn's new politics, with its claim to be based on principle over pragmatism, or you don't. This is both fatuous and, more damagingly, a gratuitous gift to the Tories."
"If I could click my fingers now and turn Britain into a non-nuclear state with a settled foreign policy based on the pursuit of conflict resolution rather than sabre rattling I would do it. That should make me a natural ally of the current leader of the Labour party, but it does not."
Corbyn is heading for a showdown with his MPs over the renewal of Britain's nuclear weapons system - with several shadow cabinet ministers hinting they would quit if the party abandons its commitment to Trident.
Last week anti-Trident shadow defence secretary Emily Thornberry was loudly heckled by Labour MPs at a meeting of the Parliamentary Labour Party - with one former minister branding her a "embarrassment".
Labour's division over the future of Trident has been ruthlessly exploited by David Cameron, who branded the party's position "ludicrous".
In his blog, Price warned Labour that supporting Corbyn's wish to see Labour revert to a policy of unilateralism would actually make the deployment of the Trident successor a "certainty".
He said: "If Labour heads to the polls in 2020 with a unilateralist defence policy and a leader who makes it clear he would never use the deterrent while he was prime minister, that election would inevitably become a referendum on whether Britain should remain a nuclear power.
"Just as inevitably Labour would not just lose, but lose massively. We've tried it before, in 1983 and 1987, under leaders who were a lot more popular then than Mr Corbyn is now."
"Call me defeatist if you like, but I'm no fan of suicide missions. Labour would lose seats on an industrial scale. Any hope of winning in 2025 would evaporate. The Tories would be in until 2030 if not longer. Trident renewal would go ahead, the new Successor class submarines would be at sea and fully operational and keeping a Rolls Royce deterrent, with all the costs involved, would become the settled policy of the United Kingdom."
"A Labour government committed to supporting Trident only as long as there is a sufficient consensus that it adds to our national security, coupled with a serious re-evaluation in office of our strategic role in the world, would be infinitely preferable to a crushing if valiant defeat."