THE depth of the divide within Labour has been laid bare with Chris Leslie, the Shadow Chancellor, warning that the “starry-eyed, hard left” strategy of so-called Corbynomics would hand the Tories at least another decade in power.

Not only that, argued Mr Leslie, but the veteran left-winger's economic strategy would push up inflation and interest rates, hitting the poorest hardest.

The frontbencher, who is supporting Yvette Cooper for the leadership, made clear that, like several other high-profile colleagues, he would not serve in a Corbyn Shadow Cabinet.

"It would be a very different political party; it would not be the party I joined. But I would fight and stay to make sure we advocated thoughtfully why a centre-left agenda is the right way forward,” explained Mr Leslie.

He went on: "Economic credibility isn't just about winning at all costs. There are reasons for caring about it, attending to those issues, rather than adopting ill thought through policies that, in the end, will hurt those on the lowest incomes, because those cost of living questions matter a massive amount.”

The Nottingham MP added: "We need a credible Labour prime minister and this is why party members have got to think carefully because so much is at stake here."

Elsewhere, Labour colleague John Woodcock, who is backing modernising candidate Liz Kendall, said he was concerned under Mr Corbyn the party would take a “massive leap back to the politics of Michael Foot and the 1980s".

The broadsides came after Kezia Dugdale, the favourite to take over as Scottish Labour leader, argued at the weekend a Corbyn victory could reduce Labour to “carping on the sidelines” for years.

The warnings against a Corbyn victory stood in stark contrast to remarks from Ken Livingstone, the former London Mayor, who claimed his fellow leftwinger had “electrified” the contest and was Labour’s best chance of winning the 2020 General Election.

He added: “We will not win in Scotland or with doubtful voters who switched to Ukip, if we do not have clear values.”

Other allies of Mr Corbyn rallied to defend Corbynomics. Richard Murphy, an economic adviser to the London MP’s campaign, said Mr Leslie had "got this completely wrong" over his rival’s plan for "people's quantitative easing"; ploughing money into housing and infrastructure.

"The real question for Chris Leslie is - why did you support £375 billion for the banks? - when actually very much less would create jobs in every constituency throughout the UK, which is precisely what Jeremy Corbyn is offering by adopting this programme."

Labour’s Richard Burgon, who represents Leeds East, claimed it was unfair of Mr Woodcock to characterise Mr Corbyn’s campaign as a return to the 1980s.

"If there's any travelling back in time going on, it's the travelling back in time to the stale, out-dated Blairite 1990s; and what perhaps did work electorally in the 1990s wouldn't necessarily work now."

But David Winnick, who described himself as being of the “broad Left”, stressed that it was not only those on the right of the party who feared a Corbyn victory on September 12.

Stressing the need to appeal to people outside of Labour’s comfort zone, he said: "I have much fear and anxiety that Jeremy will not appeal to the large section of the nation that we need to win over."

Meantime, Andy Burnham, who will launch his own election manifesto tomorrow, has announced that cheaper train tickets for part-time workers will be among a package of measures aimed at helping parents juggle jobs and family life.

The would-be party leader will make securing cut-price rail season tickets for people who only commute for part of the week a key commitment in his leadership bid.

The Shadow Health Secretary's pitch will also include a pledge to review the cost and standard of childcare and enabling employees to request flexible working from the very first day in a job rather than after six months as at present.