Hundreds turn out for Labour leader favourite Jeremy Corbyn in Llandudno

Mr Corbyn’s rivals have voiced concern over the motives of tens of thousands of people who rushed to join Labour as full members or £3 supporters to get a vote in the leadership contest.

What is more distressing is the unclear nature of whether these complaints are legitimate – or represent a last-ditch attempt to stop the left-winger Jeremy Corbyn becoming leader.

As the polls stand Mr Corbyn has enough support to win without the need to count second preferences – with Andy Burnham attracting 21 per cent of the vote, Yvette Cooper with 18 per cent and Liz Kendall polling only eight per cent.

Labour MP Diane Abbott, a supporter of Mr Corbyn, suggested Mr Blair’s comments “might be counter-productive”, while d eputy leader hopeful Angela Eagle cautioned: “Using apocalyptic language isn’t very helpful”.

The times of Ms Cooper and Mr Burnham’s visit are yet to be confirmed.

Personally I do not think Liz Kendall or Jeremy Corbyn have what it takes to unite and lead the Labour party to victory, although I will respect the democratic mandate of the victor, regardless of who it is.

The result of the contest will be announced on September 12 at a special Labour Party conference.

The bearded Jeremy Corbyn has ridden a surge of support from young people and new Labour supporters to move from being a rank outsider to the frontrunner to succeed Ed Miliband, who resigned after losing May’s general election to Prime Minister David Cameron’s Conservatives.

It is the beginning of the end of the Labour leadership race as the party sends out its ballot papers today (14 August).

The shadow home secretary insisted a “more feminist approach” is needed for the economy to ensure work fits around families as she attempted to pitch herself as the radical and credible candidate.

Mr Blair said: “If Jeremy Corbyn becomes leader, it won’t be a defeat like 1983 or 2015 at the next election”.

When registrations ended on Wednesday there were almost 611,000 people signed up to vote in the contest.

But the only Welsh MP to nominate him – Huw Irranca-Davies – said he only did so to ensure a broad range of candidates, and that he intended to vote for Ms Cooper.

Mr Blair’s success in removing the old “Clause IV” was seen as a key moment in the New Labour project leading up to its 1997 landslide but Mr Corbyn has called for the party to be more positive about state intervention.