Labour heavyweights have spelled out their hopes for the leadership contest – saying keeping the party united is as simple as ABC: Anyone But Corbyn.

They warned the party risks a repeat of its 1981 split as it tears itself apart amid the infighting and mudslinging since Jeremy Corbyn entered the race.

And they said Labour faces being wiped out at the polls if the leftwinger wins the September election.

Civil war has broken out inside the party as grassroots support for Jeremy Corbyn grows, with heavyweights warning it risks a repeat of its 1981 split (Picture credit: Sunday Mirror)

One Shadow minister said: “It has to be anyone but Corbyn. He would be a disaster. If he wins, Labour faces certain electoral oblivion. Victory for him would make our 2015 election result look like a stunning triumph.”

Today leadership contender Andy Burnham said Labour was “at a fork in the road” with a “real risk” it could split if dragged in the wrong direction.

He told the Sunday Mirror: “People who are being hit hard by this Tory government urgently need Labour to get its act together.

“Becoming a party of protest riven by factions is of no use to them whatsoever. If that is what happens, they will conclude Labour has become irrelevant – and they would be right.”

Former Home Secretary David Blunkett dismissed Mr Corbyn, 66, as the candidate of the Old Left with few answers to the problems facing the nation today.

And he boosted former Health Secretary Mr Burnham by saying he will back him for the leadership.

The warnings came after seven Shadow Cabinet ministers vowed never to serve under Mr Corbyn, and two revealed there was already a plot for an instant coup against him after a shock poll put him on course to win.

But Lord Owen, one of the “Gang of Four” who quit Labour in 1981 to form the SDP, warned today that any move to topple Mr Corbyn if he became leader would make another split more likely.

“Don’t get sucked into the bitterness, the hostility and the craziness,” he advised the Labour Party.

“They don’t want things to get out of control like it did for us in 1981. It was a tragedy. We lost all the friendships so quickly.

“Had the split not happened with the SDP, it would have made a difference. We wouldn’t have won in 1983, or in 1987 but we could have won in 1992.

“But it’s not a case of don’t split at any cost. If the policies of the party emerge and put the country at risk – like they did in the 1980s – then you have a platform people won’t stand on. Your party is important – but your country is far more important.

“There’s no doubt there’s support for Jeremy Corbyn. The polls have definitely picked up that the Labour Party has moved its centre of gravity away from what it has been.

“It had to change. We saw that in the choice of Ed Miliband and we’ll see it again.

“They have to remember that all four of these candidates are decent people. But Jeremy Corbyn has not got enough support in the PLP to be an effective leader.

“It’s not just a question of the 35 on the nomination paper. You need a lot more than that.

“In my view they will choose Andy Burham or Yvette Cooper. Both of them have been in cabinet. Both of them have been chief secretary to the treasury. In that position they’ve looked at the whole of government spending.

“They’re serious people and I’d be perfectly happy with which ever one got the job.”

Latest figures put Islington MP Mr Corbyn in front with the support of 103 constituency Labour parties compared with 97 for Mr Burnham, 86 for Yvette Cooper and 14 for Liz Kendall.

But Labour strategists fear his plan to renationalise key industries, planned tax rises and his refusal to rule out backing a campaign to pull Britain out of the EU will frighten off key voters.

Party managers are alarmed about his vow to scrap Britain’s Trident nuclear deterrent and his description of Palestinian terror group Hamas as “friends”.

Mr Corbyn’s suggestion that Britain could learn from anti-austerity parties like Greece’s Syriza – despite the economic chaos there – has also damaged Labour’s efforts to restore its economic credibility, say insiders.

Last week Tony Blair stepped into the row, warning that anyone who felt their hearts were with Mr Corbyn should “get a transplant”.

But Mr Corbyn shrugged off Mr Blair’s “rather silly remarks”.

One ally said: “All this ‘Anyone But Corbyn’ stuff shows just how worried the other candidates are.”

Mr Corbyn is expected to hit back with an appearance on BBC1’s Andrew Marr show on Sunday.

While Mr Corbyn came first in last week’s YouGov poll, the same poll found just one in 20 of his supporters believed he was the best chance of Labour winning the 2020 election.

And bookmakers said he “might have had his moment in the sun” as his odds drifted and put him in third place.

William Hill said Mr Burnham was the even-money favourite, with Ms Cooper second at 9/4, followed by Mr Corbyn at 5/2 and Ms Kendall at 25/1.

One senior Labour MP said tonight: “Roll on September 12 when we can put all this idiocy behind us.”