After a motion of no confidence in Jeremy Corbyn passed at 172 votes to 40, a Labour leadership election looks on the cards. With Corbyn vowing to stand again, his opponents hope that -- post-Brexit -- a high enough proportion of the membership will choose to oust him.

Yet in a sign that a lot of the grassroots support remains for Corbyn, the trade unions are preparing to stand by their man. After the vote results were announced on Tuesday, Len McCluskey told MPs that if they wish to contest a Labour leadership, it must be done 'democratically through an election, not through resignations and pointless posturing'. He warned that 'Jeremy Corbyn’s supporters throughout the movement will be ready for it'.

There is a lot of anger in the trade union movement over the way MPs have behaved towards Corbyn this week. At Monday's Momentum rally in support of Corbyn, a string of union representatives from Unite to the Fire Brigades Union pledged their allegiance to the leader. However, it was the tone of their statements about other members of the Labour party that was most striking.

While Jennie Formby, of Unite the Union, said that it was 'ridiculous' to blame Corbyn for the referendum result, Dave Ward -- the Communication Workers Union general secretary -- said the Blairite virus was 'spreading again and we need to top-up the antidote'. He went on to claim that it was 'absolutely disgraceful and appalling that the Parliamentary Labour Party MPs were organising this coup' -- describing it as 'the most indulgent self-serving type of politics'. Tosh McDonald, the president of Aslef, went further by claiming that he now found it difficult to decide who he hated the most out of Margaret Thatcher and the Parliamentary Labour Party.

While some of the statements are at best hyperbolic, it shows the problem Labour MPs face trying to replace Corbyn while retaining core support. Even a successful coup will be seen by some grassroots supporters as an establishment stitch-up. However, there is still one trump card for Corbyn's rivals to play. If Tom Watson were to run against Corbyn, it would make it difficult for the trade unions to dismiss the party's current turmoil as another Blairite plague. As a former Unite official who acts as a bridge to the trade unions, they would need to change the tone of their dialogue to be less divisive -- if not get behind him.