Andrew Grice: There was nobody to pull the trigger

Gordon Brown knew it was coming, even if he did not know the precise mechanism. As he planned his new year strategy over Christmas at his Scottish home, he guessed that the rebel backbenchers who have been trying to lever him out of Downing Street before the general election would have one more heave.

In the Brown camp, the timing of yesterday's final throw of the dice was awful, just two days after Labour in effect launched its election campaign by issuing a 148-page dossier claiming there is a £34bn black hole in David Cameron's spending plans. But from the rebels' point of view, there is never a good time for a coup. When James Purnell spectacularly quit the Cabinet last June, cabinet heavyweights did not follow him and Mr Brown survived – just.

Some ministers were swayed by warnings from Brownites that a second change of leader since the 2007 election would force an immediate general election at a time when Labour trailed badly in the opinion polls. Some Brown critics thought there would be one last chance to oust the Prime Minister around the turn of the year, when a new leader could name a date for an election that must in any case be held by June.

Yesterday, however, Brown allies used a different argument as they tried to contain the latest rebellion, led by the former cabinet ministers Patricia Hewitt and Geoff Hoon. They declared that it was now too late to change the leader because the election campaign is already under way. There is another flaw in the attempts to push Mr Brown out – a lack of co-ordination between backbenchers and cabinet ministers. There are plenty of doubts in both camps about whether he is the right man to lead Labour into the election. But in three attempts – July 2008, June last year and the one launched yesterday – the anti-Brown forces have never managed to convert the grumbling about him into a necessary mix of big backbench numbers and cabinet heavyweights such as Jack Straw, Harriet Harman, David Miliband, Alistair Darling, Alan Johnson or Lord Mandelson.

One former cabinet minister and Brown critic said last night: "It is the same catch-22. The cabinet ministers won't join in because they say there is not a big enough backbench rebellion. But lots of backbenchers say they won't go for the kill unless some in the Cabinet put their head above the parapet."

The ex-minister wants Mr Brown to go but dismissed yesterday's putsch as "another cock-up" because not enough backbench support had been lined up behind the call for a ballot of Labour MPs. The rebels say they were trying to tackle the "catch-22" problem by hoping that their destabilisation exercise would provoke a cabinet minister to resign.

Some senior Labour figures are convinced that, if all 349 Labour MPs were put on a lie detector machine and asked who should lead the party into the election, Mr Brown would not survive. In effect, that is what Ms Hewitt and Mr Hoon are demanding by calling for a secret ballot.

But everyone wants someone else to pull the trigger – especially those who might benefit from an assassination, such as Alan Johnson or David Miliband, who do not want their fingerprints on the gun. Other Brown doubters in the Cabinet fear the blood that would be spilled would be worse than soldiering on with Mr Brown.

So it probably isn't going to happen – again. Under a different leader, destabilisation might have worked. But Mr Brown is not the sort to take a hint and walk away. "It's just not in his nature," one cabinet minister said ruefully.