There was a fascinating piece from Martin Kettle in the Guardian today. The headline was slightly laboured but encapsulated the argument well: "An October revolt is plotted. Brown's head is not safe yet".
Kettle wears his Blairite loyalties on his sleeve, so it's pretty easy to see where he is getting his ministerial briefings from. He is well-connected in just the sort of places where the Prime Minister is disliked the most.
But his clear bias does not stop him from making some important points. The first is that the optimum period for a putsch against Brown is the week immediately after party conference season. As Kettle points out, the argument against the present PM leading the Labour Party into the next election has been the same for some time. At the heart of all discussion on the subject is the very real possibility that the present leadership could lead the party into a defeat so catastrophic that it will not recover.
The most significant insight is that Mandelson's arguments against a coup at the time of the reshuffle and James Purnell's resignation no longer hold. There is no fear of being rushed into an early election, because by next month the earliest an election could be realistically held would be the spring.
The Labour Party has yet to recognise it, but it is now in full-scale crisis. Somehow the presence of Peter Mandelson is allowing Labour to indulge in its habitual collective denial. By a supreme act of will, the First Secretary gives the impression that he is holding the whole edifice together. The reality is that since his return, the fortunes of the party have declined even further (although it is quite possible they would have been even worse without him.
I'm sure Martin Kettle is being told there will be another attempt on Brown's crown. But then I'm also convinced that some of the same people were saying they would go over the barricades with Purnell earlier in the year.