At last sensible Labour politicians are injecting some maturity into the leadership debate. To start with, Tony Blair’s aide John McTernan called anyone who nominated Jeremy Corbyn a “moron”, which is such a refreshing change from the divisive and childish approach of the Left.

His next statement will be that Jeremy Corbyn smells like a poo-poo and anyone who votes for him has a tiny willy, because John McTernan understands the importance of Labour appearing grown up and united.

Now Blair himself has informed us Corbyn would be a disaster. This could cause a problem, because for giving his views in a speech Blair usually charges at least £200,000, and Labour’s finances are stretched enough as it is. Normally he’s advising the government of Kazakhstan or a Saudi Arabian oil company, or shaking hands with characters like Colonel Gaddafi so it’s surprising he didn’t suggest cancelling the election and putting the army in charge of the party, and sentencing Diane Abbott to 500 lashes. Even so it’s sweet of him to take time out from his busy schedule.

He said that if your heart is telling you to vote for Corbyn, you need a heart transplant. You can see how he thinks this, because the first word anyone thinks of when they see Blair is “heart”. Tony Heart Blair is what his friends President Assad of Syria and ex-military ruler Mubarak of Egypt call him.

When you’re responsible for all the heartfelt warmth and sunshine that resulted from invading Iraq, it’s understandable if you get angry with heartless types such as Jeremy Corbyn who opposed it all along, but not everyone can live up to Blair’s standards.

Blair’s supporters point out that although his current image is tarnished, we should remember he was hugely popular in 1997.

The Blair viewpoint has clearly affected Margaret Beckett, as she’s one of the MPs who nominated Corbyn, and her response to being called a moron was to agree. She regrets helping him to stand for the election, she says, as she never guessed he would win as much support as he has. This is a novel attitude towards democracy, that the worst thing you can do in an election is allow someone to stand if they might win.

Maybe Labour should change its rules for elections again, so that anyone who disagrees with Blair is only allowed to stand if they sign a pledge to get fewer than eight votes.

Luckily, Corbyn’s opponents are making a persuasive case for their own bids. Andy Burnham is especially clear that he’s opposed to the Tory’s Welfare Bill, as it will “Hit working families” and “hit children particularly badly”. Indeed he’s so opposed to it that he was determined not to vote against it. The most effective way to oppose it, he insisted, was to abstain rather than vote against it, because that way he can unite the party against it.

It’s so rare that a politician speaks clearly like that, in a language we can all understand. Presumably he’ll be telling all his supporters not to vote for him in the leadership election, but to abstain as that way he can win by even more.

Burnham is known as an Everton fan, so when he’s at their games he must try and persuade the Everton supporters to sing “Spurs and Everton, Spurs and Everton, we’ll abstain on this one evermore, we’ll abstain on this one ever-more”, rather than fall into the trap of supporting the team he supports by supporting them.

Maybe his plan is to make Labour electable again by supporting all the different policies. If he becomes leader, Labour will support the cuts and oppose them, and oppose fox-hunting but support it as well, and that way the party can win votes from everyone.

It could be that the reason three of the candidates are struggling to make an impact is they don’t seem capable of expressing what they stand for.

Whenever they’re asked what they believe in they make grand replies such as “I want a Britain not of down but of up, for the always and not the never, that reaches out to all of us, not only people on the 133 bus, a Britain not just of the liver but also the kidney, a Britain that can care, can share, be debonair, fair, abstain on the austere, and say a prayer like Tony Blair.”

Liz Kendall makes some effort to stand for something definite, which is to be like Blair but more so, and next week she’ll probably criticise Blair for only invading Iraq once when he should have done it twice.

There are reports that Kendall has asked Yvette Cooper to drop out, as Liz stands the best chance of beating Corbyn. As every survey shows Kendall is by some distance last, that’s impressive and I might try this myself. I’ll suggest to Mo Farah that he drops out of the 5,000m in next year’s Olympics, as my time of two hours is the only one that stands a chance of beating the Kenyans.

All three are now squabbling, not about ideas or policies or even their favourite type of biscuit, but over which one has the best chance to beat Corbyn. And they must beat him, because by being capable of expressing his ideas clearly and simply, for example by voting against welfare cuts, he makes himself unelectable.

If you look at Corbyn’s record it’s clear he just can’t win elections. In his constituency of Islington North he inherited a majority of 4,456, which is now 21,194. He’s one of the few Labour MPs whose vote increased between 2005 and 2010, when he added 5,685 to his majority. This is typical of the man, defying the official Labour policy of losing votes and getting more of them instead, just to be a rebel.