They don't give up. Following the abortive #chickencoup, last month when the 172 Labour MPs signed a vote of no confidence in Jeremy Corbyn, the Labour leader's support in the party seemed if anything to grow. Then Labour’s ruling NEC tried to exclude new Labour members to weed out the “trots” as supporters of Mr Corbyn are described by so-called “moderates”. That didn't work. Now they're mounting what looks like a series of suicide attacks on Mr Corbyn.

The London Mayor, Sadiq Khan announced at the weekend he wanted Mr Corbyn removed on the eve of leadership ballot papers being sent out to members. Now Kezia Dugdale, the Scottish Labour leader, has announced she too is supporting Mr Corbyn’s rival, Owen Smith, even though he seems to have loser written all over his face. This has caused some friction because she declined to say whom she would support last time.

But it also seems somewhat futile. Mr Corbyn is miles ahead in terms of support from Labour constituency parties. No one seems to believe Mr Smith can win, and he is now being lambasted as a fraud even by virulently anti-Corbyn Labour commentators like the Telegraph's Dan Hodges. So why have the Scottish and London Labour party leaders chosen this moment to disown the odds-on favourite to win the Labour leadership election? Do they know something we don't?

Is there some scandal brewing about Mr Corbyn's tax returns? Is Labour's leadership election going to be altered again so only party members who joined under Tony Blair are allowed to vote? No – it's more likely Ms Dugdale and Mr Kahn are part of a move to prepare the party for a general election defeat they hope will kill Corbynism stone dead.

There's speculation Theresa May is about to call a snap election to consolidate her position, post Brexit. What better time than now? Labour is in terminal disarray;Team GB has just beaten China in the Olympic medals tables; the economy seems to be performing better than was forecast before the referendum. Things can surely only get worse as her ministers engage with the fraught task of taking Britain out of Europe.

Mr Corbyn is probably thinking what Mrs May is thinking too, which may explain why he has ruled out any “progressive alliance” with the SNP. Labour was damaged in the 2015 general election by those posters of Ed Miliband in Alex Salmond’s pocket, and by claims the SNP was about to grab England’s cash. Time to clear the decks.

If Labour is defeated in an early election and Mr Corbyn falls on his sword, Mr Khan might even think he's in with a shout as a future Labour leader. Mr Smith will be history and the London Mayor has shown he can win elections with “real” voters, not Labour members. Ms Dugdale needs to fight off any challenge from her Scottish left wing. But the Dugdale/Kahn strategy – if such it is - could come unstuck. For a start there's no guarantee Mr Corbyn would necessarily resign after an election defeat.

Many of Labour's 600,000 members regard Mr Corbyn as a socialist messiah and winning elections comes a poor second to defending the faith. After an election defeat, angry Corbynites might turn their wrath instead on rebel Labour MPs and prominent figures like Mr Khan for helping to make Labour unelectable. There have been rumours in Westminster Labour MPs have been having talks with Tory MPs to encourage an early election.

In Scotland the recriminations after another election defeat would be savage if it appeared UK Labour MPs had connived at the return of a Tory government. The divisions are on open display this week as Mr Corbyn comes to Scotland for a hustings debate with Mr Smith. Ms Dugdale is standing well clear while the left Labour MSP, Neil Findlay, will be promoting Mr Corbyn's every move.

Scottish Labour Party looks to be the next casualty of Labour’s civil war. The Scottish Labour Party has a claimed membership of 23,000 which is about one fifth of the SNP's. It is just too small to cope with an ideological divide as deep as this. But it is hard to see how the party can maintain any semblance of unity when the elected members in Westminster are so at odds with the party members.

If Labour MPs and MSPs launch a scorched earth policy it is Nicola Sturgeon who will inherit the desert.