All the focus in recent weeks has been on the Labour leadership race.
However there has been an equally bitterly fought, and in many ways far more interesting battle taking place to select Labour's London mayoral candidate.
All the bookies currently have Tessa Jowell as the favourite to win that race. But is she really? Is the same party about to crown the leadership to the hard left Jeremy Corbyn, also about to crown the mayoral nomination to an ardent Blairite?
There are several reasons to believe not. The main one is the huge influx of new members and supporters who have joined the party since May. Labour sources tell Politics.co.uk, the size of the London 'selectorate' able to choose Labour's mayoral candidate has roughly tripled since the general election. Of these new members, the overwhelming majority (up to 70%) are Corbyn supporters, according to canvassing returns by Jowell's rivals.
Instinctively, this new surge of left-leaning supporters, would appear to benefit Jowell's rivals at her expense. In recent days Ken Livingstone emailed London Labour members urging them to back Corbyn nationally and Sadiq Khan locally. The impact of Ken's endorsement was somewhat muted by Khan's decision during an LBC debate last week to state that he would "probably not" work inside a Corbyn shadow cabinet. Khan's aides now say he was merely stating his unwillingness to serve in the shadow cabinet generally, rather than rejecting Corbyn in particular. However, that blip aside, Livingstone Khan's supporters claim Livingstone's endorsement is having an effect on members. A source in Khan's camp claimed the vast majority of Corbyn supporters they have spoken to are now backing Khan and Abbott rather than Jowell. They add that Jowell's lead is mostly among longer-term members who joined the party before May. Among the majority of new members and supporters, Jowell is well behind.
Jowell's backers deny this and claim her support is roughly the same among both new and older members. There is certainly reason for optimism on their side. Contrary to the stereotype, most Corbyn supporters are very far from being hard-left borderline Trotskyites. Many are simply left-leaning but independently minded and in many ways non-political Labour supporters.
Indeed, strange as it may sound, many Labour members are not really that 'political' in the traditional sense. Evidence for this can be found in 2010 when London Labour members backed David Miliband for leader, while also overwhelmingly backing his political opposite in Livingstone This is something which has been missed in the national debate about Corbyn. One of the main reasons he is gathering so much support is not just because of his left-wing politics, but because many members simply find him to be the most convincing candidate, regardless of politics.
However, the kind of mass enthusiasm seen for Corbyn has not been reflected in support for either Jowell or any of her rivals. Jowell's campaign events have in some cases been very sparsely attended. Despite receiving lots of resources from the Progress wing of the party, Jowell supporters also report some difficulty in getting enough Labour activists to physically man phone banks. With so much attention being focused on the two national leadership races taking place at the same time, Labour's London mayoral race has suffered.
Jowell's rivals demonstrate little sign of manning a mass grassroots movement either. Khan, who has the support of both Ken's machine and the trade unions, has a rather small social media presence. Despite impressive performances in the hustings, both David Lammy and Diane Abbott also appear to have failed to harness the energy of the Corbyn movement. Even Christian Wolmar, who is the closest to a Corbyn-style outsider figure in the race, has struggled to get the kind of exposure and support necessary to make a serious grassroots challenge to the leading contenders.
If there is excitement about Labour's mayoral race within the London Labour party, it is keeping itself well hidden. Yet in such a muted race, the influence of the unions and the influx of Corbyn supporters could be decisive. Team Khan's claims of momentum were given some force by a new Survation poll out yesterday showing Khan well ahead of Zac Goldsmith among voters. However, the size of the Corbyn-effect is still difficult to tell. The only official polling we have seen so far has been of the general public. The relatively small size of the London selectorate has made it too difficult for YouGov and others to accurately poll the race. The only other source we have is Labourlist's online surveys, which at least one of the candidates has boasted openly about filling with their own supporters.
But in the absence of any firm conflicting evidence, the race does appear still to be Jowell's to lose. The only question is whether the Corbyn surge could be enough to lose it for her.