Politics is not fair. I thought that Andy Burnham’s position on the Welfare Bill was perfectly reasonable: he made it clear that a Burnham-led Labour party would have opposed the Bill, but demonstrated the loyalty that he will expect from his own frontbenchers. In any case, his position was identical to that adopted by Yvette Cooper and Liz Kendall, although both made less noise about it.

But I don’t decide who wins the Labour leadership election. The Welfare Bill has delivered a body blow to the Burnham campaign: from in a close race for first place in local party nominations, a strong second place in both public and private polls, to a struggle not to finish third behind Cooper. A private poll, leaked to the Mirror, shows Burnham slipping to third place. “Andy’s lost, hasn’t he?” was the message from one Labour insider late last night.

The pattern in local parties since the Welfare Bill is clear: Burnham in retreat, finishing a poor third in most races, and, more troublingly still, fourth in London, where Labour membership is highest. A survey by Labour International – the local party that represents ex-patriate Labour party members – found him in third place.

Of course, private polls are hard to judge unless we can see the data for ourselves. Labour International’s email survey is self-selecting. And perhaps Burnham supporters just haven’t felt motivated to turn up to nomination meetings in recent weeks.

It’s certainly possible that the increasing hostility towards Burnham on social media, the leaked poll, the public surveys, and his weakening position in local Labour parties are all coincidental. It just doesn’t seem all that likely.

That’s superficially good news for Yvette Cooper, who now seems to be on course to face Jeremy Corbyn in the final round of Labour’s leadership election. But again, the evidence from local party nominations makes for grim reading for her campaign: Cooper is everyone’s second choice – apart from supporters of Andy Burnham. When Liz Kendall goes out, her transfers go to Cooper. When Corbyn goes out, his transfers go to Cooper.

But when Burnham goes out, his support switches to Corbyn. I wrote at the start of the week that I felt increasingly certain that Corbyn was on course to win the Labour leadership election. A week in which the candidates to his right have squabbled about which candidate is most well-placed to stop him, figures from the Blairite past have speculated about displacing him in a putsch immediately after he wins, and the candidate with the biggest pool of second preferences appears to have drifted outof contention have only strengthened his chances.