A victory for Jeremy Corbyn could split the Labour Party in two, Yvette Cooper has warned.

Noting how the left-winger during his time at Westminster had voted against his own party more than 500 times, the Shadow Home Secretary stressed how her colleague had "not shown any ability" to be part of a team.

The divisions within the party have already become stark; even before the result is announced at London’s QEII Centre on September 12.

Senior figures on the right of the party are said to be preparing their opposition to the Islington North MP, if he succeeds in his bid to succeed Ed Miliband, by forming the Labour for the Common Good group, dubbed "The Resistance". Its members already include frontbenchers Chuka Umunna and Tristram Hunt.

Ms Cooper as well her fellow candidate Liz Kendall have said they would not serve in a Corbyn Shadow Cabinet; so too have Mr Umunna and Shadow Chancellor Chris Leslie.

One senior source branded Mr Corbyn “clueless” and “10 times worse than Michael Foot” while another told The Herald the leftwinger, if he won the Labour crown, would last only 18 months. “It’s going to be absolutely awful for the party if Jeremy wins,” he said.

In contrast, Mr Corbyn's supporters, claimed the British political class was "frozen with fear" at the prospect of the London MP winning the Labour crown and claimed a smear campaign was under way to stop him.

In a BBC interview, Ms Cooper was asked if she was genuinely worried that the party would split if Mr Corbyn won. She replied: "I am, because I'm worried what's happening at the moment, that the party does seem to be polarising between the different extremes and I don't think that is the right thing to do.

"Partly, we want to hold our party together in order to win. Divided parties don't win, but it's actually much more than that. I just don't think the extremes of the party are the right place to be and are true to our values and are true to the things we need to do to change the country for the future."

In Scotland, senior figures have factored in a landslide defeat for Labour at the Holyrood elections next May although some believe a Corbyn victory could begin to draw back the Nationalist tide. However, others predict the key test will come next spring in England with the local elections; a further slide there could be the beginning of the end for a short-lived Corbyn leadership.

On Wednesday, the leftwinger was forced to admit associating with Lebanese extremist Dyab Abou Jahjah after a photograph emerged of them together; yet he insisted he had no recollection of their meetings.

Diane Abbott, the London Mayoral hopeful, who is one of Mr Corbyn's most prominent supporters, said accusations about the frontrunner's associations with extremists such as Mr Abou Jahjah and Palestinian militant group Hamas had surfaced because opponents were terrified he would take the top job.

“The British political class is frozen with fear at the idea that Jeremy will actually win this leadership election,” declared the fellow London MP.

"It's by no means certain but the very notion of it terrifies people because the energy behind him has the power to disrupt and to change and transform politics. This is where these anti-Semitic smears come from," she added.

Meantime, as another batch of ballots went out, some registered Labour supporters vented their anger at receiving notification that they were being barred from taking part. The party has brought in extra staff to vet applications from the 120,000 or so people, who are not members but who paid a £3 fee to participate.

*William Hill, which had originally quoted Mr Corbyn as a rank outside at 200/1, has now made him the clear favourite at 8/11 to win.