Clearly the prospect that Jeremy Corbyn might win the Labour leadership election is the most exciting thing in British politics right now. So I will blog about it for the third successive post. This time I want to look at what all this means for the Lib Dems.
According to the rather lazy analysis you often see out there, such a development would be a bonanza for the party. Labour grandee Jack Straw has suggested as much, in a desperate attempt to persuade Labour activists to vote for somebody else. The logic goes something like this. If Mr Corbyn wins, centrist Labour types will be without a political home. They will not be able to bear the leftward lurch implied by an influx of new activists, and, perhaps more sinisterly, the growing influence of trade unions. So, the Lib Dems, being a left of centre party under its new leader, Tim Farron, is natural place to go. It is now exorcised of coalition with the hated Tories - and even that coalition might be seen in a kinder light, now the Tories are unrestrained in government. And this will create an appealing alternative to the Conservatives that would draw floating voters in.
So what would be the political scene if Mr Corbyn won? The left would be cock-a-hoop, and they would have that much-prized thing: momentum. Many people have doubts about the current conventional wisdoms about economic policy - so they might give this new Labour a hearing. This would be bad for the Lib Dems in the short term, as the party would be overshadowed. Disillusioned Labourites are not going to flock to the Lib Dems in the short term either; they will still be in grief for their own party, and may hope that Mr Corbyn can be ousted.
But could that momentum be maintained? The British press, which still sets the media agenda, would be fiercely critical, and it would not take them long to find policy issues that put the new Labour leadership in a bad light. Mr Corbyn has spent his entire political life in the fringes of politics, where saying silly things is rewarded rather than punished. That gives the press plenty of material to work with. Furthermore, there would be a certain amount of chaos in the Labour party, as it argues over a whole range of issues. There are bound to be many disgruntled MPs. Voters may or may not disagree with the party's new policies, but the real danger is that it starts to look incoherent and incompetent. These voters will not be part of the internet echo-chamber where left-wing activists will convince themselves that they are riding a popular wave - and they may not see the danger until too late.
The Lib Dems would be quite well placed to exploit this, in principle. The Greens' thunder will have been stolen by Labour's new direction; Labour will have taken over most of the Greens' populist agenda. Ukip have lost momentum, with their rather chaotic General Election performance.
But the Lib Dems have two big problems of their own. First the party is very weak. Second it remains divided over its recent history.
The most conspicuous sign of weakness for the Lib Dems is its mere eight MPs, the lowest number for generations. This does not get better on closer examination. There were very few second places in May's general election, and many lost deposits. The local councillor base has been hollowed out. Ruthless targeting over many years (and from well before the 2010 General Election from when the serious trouble started) has hollowed the party out in the majority of the country. This weakness makes it much harder to exploit any bounce in the party's wider support. It also undermines the party's basic credibility. Disillusioned Labourites may be tempted to set up their own party rather than join a weak and flailing one.
This is compounded by the party's confusion over what it stands for. Its core values are firm enough, but the party's interpretation of recent history is not. Was Nick Clegg's leadership, and coalition with the Conservatives, a betrayal of the party's values that should be expunged, with a suitable purge of those responsible? Just read a few articles in Liberator magazine, or read online comments, and you will see that this is a popular view amongst many in the party, and those who have left the party and could rejoin. Or is that coalition the proudest moment in the party's recent history, when the party put the country before its own interests, and marred only by a few tactical errors? This view too is widespread, especially amongst those that stuck with the party, and many who have recently joined it. Some kind of reconciliation between these opposing views (that I will call the rejectionists and the coalitionists as a convenient shorthand) has to be engineered or the party will look just as fractious as its Labour competitor.
Interestingly, the outcome of the Labour leadership contest does have some bearing on this contest. However much Lib Dem activists want the party to plough its own furrow, it inevitably moves into the cracks left by the others. A victory for Mr Corbyn would be bad for the rejectionists. It would steal their thunder, and undermine their efforts to turn the Lib Dems into a party of the radical left. To be sure there are big differences between the Lib Dem rejectionists and the Corbynistas. The former are much more wary of state power, and emphasise political reform, especially electoral reform to a much greater extent, rather than the political control of the levers of power. And yet they are both competitors for those who are impatient for change. Meanwhile, of course, a Corbyn victory would give a ready new audience for the coalitionists - for people who are more patient, pragmatic and common sensical about the progress.
On the other hand a victory for for Andy Burnham or Yvette Cooper would be a boost for the rejectionist Lib Dems. They would appeal to disillusioned Labour leftists outside the hard core, while more moderate Labourites would continue to place their hopes in Labour,rather than turning to the Lib Dems. Should a Corbyn leadership collapse, and be replaced by something more mainstream (Chukka Umunna is sometimes mentioned) then this dynamic might also come forward. On the other hand a Corbyn collapse followed by a charismatic new Labour leader (whether or not Mr Umunna fits that bill is debatable) could be the worst outcome for the Lib Dems of both camps.
The Lib Dem leader is treading a careful path between the rejectionists and the coalitionists. And many Lib Dems were perhaps hoping for a period below the media radar when the party could gather itself together and consolidate its identity. In the jargon, the party would rebuild its core, rather than bid for the political centre (i.e. floating voters). Too rapid a collapse of the Labour Party could place unbearable strains on the Lib Dems, both in terms of organisation and the party's coherence.
But a slow motion Labour collapse could be an opportunity for the Lib Dems. Even so, it will be a major challenge for this badly wounded party to do it justice.