In the lather of excitement caused by David Miliband's article in the Guardian, everyone has forgotten just how difficult it is to remove a Labour leader against his will. Or perhaps they simply don't know - ignorance in the press of how the Labour party works is breathtaking, especially when you consider that Labour has been governing for the last eleven years.
If you want to remove a Labour leader against his will, potential candidates need to gather nominations of 20% of MPs (currently 71 MPs). Then a majority of Labour party members need to vote in favour of having a leadership election at the party conference. Only then can the general secretary be informed, and I think another vote from the members is required before the election proper can proceed.
Therefore a leadership challenge can't take place without a majority of members agreeing to the challenge. Essentially the leader gets to appeal over the heads of MPs to the members, who are all volunteers, and who belong to the party because they believe in the Labour movement, not because their careers/incomes depend on it in the manner of the MPs. This makes the Labour party a completely different animal from the Tories and LibDems, where it is purely up to MPs to mount a challenge.
This is the main reason Brown never moved against Blair prior to Blair pre-announcing his retirement in late 2004. Blair had the option of appealing to the members, who would almost certainly have slapped the challenge down. It wasn't till 2006 and Lebanon that the membership started to get fed-up with Blair (Iraq only made a small dent, because most dissenting members chose to leave, and if you leave, you cease to have any power over the Labour party).
Of course if the leader resigns, it's a different story. You then simply need 12.5% of MPs to nominate you (currently 44MPs), and then the election proper starts, and you have to win the three electoral colleges. That too is pretty difficult, as each college is quite different in character; the working classes are mainly represented by the unions, the middle classes are concentrated in the constituency parties, and then you have the MP's in the third college.
In the Labour party, leaders are rarely challenged - I think the last time there was a successful challenge was at the party conference of 1935, when Lansbury, a pacifist, was defeated in a vote led by Ernest Bevin, a hawkish anti-fascist anti-appeaser. Lansbury resigned after losing the vote and was replaced by Attlee. But it was a dramatic era - at stake was the evil represented by Hitler, who had decimated the German trade unions and whom Bevin and Attlee believed was a dangerous warmonger. Removing Lansbury meant that Labour could vote against appeasement, while the Tories voted in favour, which in turn led to a disgusted electorate purging parliament of Tory appeasers in 1945 and giving Labour a massive majority - so you could argue it was worth deposing Lansbury. Attlee and Gaitskill also faced leadership challenges, but they came to nothing. And as time proceded challenges became rarer and rarer. Most Labour leaders are allowed to face the electorate in at least one election and even if they lose, they sometimes get another go. Wilson, a sitting prime minister, announced his retirement suddenly, and Blair pre-announced his retirement in late 2004, taking everyone by surprise.
So we are in new territory here. I think the press are simply expecting Gordon Brown to resign. However, he could choose to stick to the rules and invoke the appeal to the membership. It's high stakes, but if the constituency members decide they don't want a leadership challenge, Brown's position would be immensely strengthened. When he became leader because of overwhelming nominations from MPs, members didn't get to vote. Winning a member vote not to have his leadership challenged would therefore enhance his legitimacy. Would Brown wish to risk it? Only he knows how fed-up he is of the current situation.
Would members vote to refuse permission for a leadership challenge? No one knows. Many members are uneasy. They don't know what changing the leader this soon and in this manner, would do to Labour's prospects. They would also shy from humiliating Brown, who lets face it, has done a tremendous amount for the Labour party and the Labour government over the last 15 years. Members are always less ruthless than MPs. It's worth remembering that had Thatcher had the ability to appeal to her members in a similar fashion, she would have stayed...
The whole business is fraught. I fear that people are so unused to Labour challenges that they have not thought through the implications. It's easy I suppose, over beers with journalists who are only familiar with Tory leadership challenges, to get carried away and not to realise just how tough this is going to be.