Tony Blair has warned Labour supporters to reject the “Alice in Wonderland” appeal of Jeremy Corbyn or risk driving the party into an abyss.
In defiance of appeals from the left-winger’s leadership rivals to resist further interventions, he issued a fresh warning the party would become unelectable.
Writing in The Observer, the former prime minister conceded that appeals from himself and ex-leaders Gordon Brown and Neil Kinnock appeared only to have emboldened those who have propelled the veteran MP from rank outsider to frontrunner to succeed Ed Miliband.
He accepted that he had as yet failed to understand the “powerful” phenomenon behind the serial rebel’s popularity or how best to respond to it.
But he mocked those behind it for embracing a “politics of parallel reality ... in which reason is an irritation, evidence a distraction, emotional impact is king and the only thing that counts is feeling good about it all”.
With less than two weeks until the result of the election is announced, Mr Corbyn remains the bookmakers’ overwhelming favourite to pull off a shock win over experienced former cabinet ministers Andy Burnham and Yvette Cooper.
Liz Kendall, the most Blairite of the candidates, is on course to finish a distant fourth.
Stark warnings from Mr Blair - who previously said people whose heart was with Mr Corbyn should “get a transplant” - have done nothing to dent the left-winger’s shock lead and have been attacked as unhelpful by his mainstream rivals.
An angry Mr Blair - who made significant reforms to the party and led it to three consecutive general election victories - insisted however that it was important to speak out to prevent the party repeating past mistakes.
All the evidence showed Labour lost the 2015 election because it was “anti-business and too left” and had no credible economic plan, he said.
“Neil Kinnock, Gordon Brown and I have collectively around 150 years of Labour party membership. We’re very different. We disagree on certain things. But on this we’re agreed,” he wrote.
“Anyone listening? Nope. In fact, the opposite. It actually makes them more likely to support him.
“It is like a driver coming to a roadblock on a road they’ve never travelled before and three grizzled veterans say: ‘Don’t go any further, we have been up and down this road many times and we’re warning you there are falling rocks, mudslides, dangerous hairpin bends and then a sheer drop’.
“And the driver says: ‘Screw you, stop patronising me. I know what I’m doing.’
“In the Alice in Wonderland world this parallel reality has created, it is we who are backward looking for pointing out that the Corbyn programme is exactly what we fought and lost on 30 years ago, not him for having it.”
Mr Blair said he had been urged not to “blah on about winning elections; it really offends them”, adding: “It would actually be quite funny if it weren’t tragic.”
He likened the surge for Mr Corbyn to movements that had propelled the Scottish National Party to dominance in Scotland, fuelled the re-emergence of Marine Le Pen’s far-right National Front in France and helped Donald Trump and Bernie Sanders emerge as contenders in the US presidential race.
“They’re making all those ‘in authority’ feel their anger and their power. There is a sense of real change because of course the impact on politics is indeed real. The Labour party is now effectively a changed political party over the space of three months.
“However, it doesn’t alter the ‘real’ reality. It provides a refuge from it.
“Because Trump and Sanders aren’t going to be president; Scotland did vote No and even if it votes Yes in the future, the pain of separation for all of us will be acute; Syriza may win but only by switching realities; and Jeremy Corbyn is not going to be prime minister of the UK.
“And Le Pen as French president? Let us hope not because that collision with ‘real’ reality will be brutal for all of Europe.”
Mr Blair said he did not know whether the answer was to confront the phenomenon or seek to build bridges between the two “realities”.
“But the answer will preoccupy the Labour party for years to come, provided that the space to examine it is permitted,” he concluded.
Mr Burnham, who previously criticised Mr Blair for making “dire predictions” of the consequences of victory for Mr Corbyn, said Labour would be mad not to listen now to the former prime minister.
“Tony Blair won three general elections for Labour. If we have got to a point now where the Labour Party says it doesn’t want to listen to him then I would think we have lost the plot,” he told the Murnaghan show on Sky News.
“We have got to listen to people who have been there in the past and seen Labour when it had difficulties in times gone by. People like Neil Kinnock who were there in the mid-1980s when Labour did start fighting itself and left the pitch clear for Margaret Thatcher to bulldoze her way through communities.
“We don’t want to go back to that and let the heirs to Thatcher, Cameron and Osborne, do the same.”
Unlike Mr Blair however, Mr Burnham said he did understand the reasons behind Mr Corbyn’s popularity: a “deep disillusionment” with Westminster politics where the main parties were “a pale imitation of each other”.
But electing his rival risked leaving the Conservatives in power for two decades, he suggested.
Jennie Formby, political director of the Unite trade union, dismissed Mr Blair’s intervention.
“Sorry Andy Burnham; I totally disagree that neo-liberal multi-millionaire war-mongerer Blair has anything useful to say,” she wrote on Twitter.
“He hasn’t said anything constructive or useful so far re leadership campaign, you can’t just write off tens of thousands supporting JC.”
The Corbyn camp said it now had more than 15,000 registered volunteers and had raised £180,000 in donations via the campaign website - with the average donation being just over £23.
More than 30,000 had attended his rallies so far, they added.