RICHARD Leonard has been abandoned by his own union on the eve of a vote which could end his leadership of Scottish Labour.

GMB Scotland, which supported Mr Leonard’s leadership bid in 2017, refused to back him ahead of a confidence vote at the party’s ruling body.

It said its members would “not thank us for getting bogged down in an internal Scottish Labour party issue”. 

General Secretary Gary Smith also told the Guardian that Labour faced an “existential crisis” north of the border, and most of his union members now voted SNP.

Mr Leonard is struggling to contain a mutiny within his ranks over his leadership performance and Scottish Labour’s prospects at next May’s Holyrood election.

With polls putting the party on 14 per cent and Mr Leonard still unknown to most Scots after three years in charge, four of his MSPs last week urged him to stand down to avoid an electoral “catastrophe” in May.

However Mr Leonard, a pro-Corbyn left-winger who became Scottish leader just 18 months after being elected a Central Scotland list MSP, has refused to back down, attacking his critics as “despicable” and threatening them with deselection.

Tomorrow’s meeting of the party’s Scottish Executive Committee is now set for a showdown, with around a third of its 32 members signing a no confidence motion.

The rebels hope to force Mr Leonard to resign or agree to a leadership contest.

Before he entered Holyrood, Mr Leonard was a senior GMB officer for 20 years, and the union gave him £12,000 and a phone bank to canvas members in the 2017 contest.

He remains a GMB members, regularly declaring his membership as an interest at FMQs.

He has been backed by Scotland’s biggest unions, Unison and Unite, in the internal feud.

However Mr Smith, who is close to Mr Leonard’s more moderate deputy Jackie Ballie, made it clear that the GMB would not be joining them.

He told the Guardian: “At a time like this, our members would not thank us for getting bogged down in an internal Scottish Labour party issue, a party for which many of them no longer vote for. The truth is Scottish Labour’s problems run far deeper than one individual. 

“It is facing an existential crisis in Scotland and the knock-on effect for the UK party could be quite profound.”

Mr Leonard said: "The last thing Labour supporters and those we need to win back want to see is a party turning in on itself.

"A lot of these people are not mandated by their organisations to vote in this way.

"That exposes how this is motivated by faction and that this is an entirely factional move

"They have nothing to say or offer, no ideas, no plan to protect jobs and living standards against the backdrop of the Covid crisis.

"That is what I want us to concentrate on: the real struggle the people of Scotland are in."

Four MSPs - James Kelly, Jenny Marra, Daniel Johnson and Mark Griffin - and four Labour peers have so far called for Mr Leonard to quit for the good of his party. 

Polls suggest Scottish Labour is on course to lose six of the 24 MSPs it won in 2016.

It lost both its MEPs and six of its MPs in elections last year.

The left-wing Momemtum campaign today backed Mr Leonard.

In a series of  tweets, it said: "Solidarity with Richard Leonard. We all know that divided parties don't win elections - this attempted coup will only hurt Labour.

"The people behind this know it, but care more about their own careers and stopping socialists being listed in the Holyrood elections.

This is about self interest and control of the list selections for Members of Scottish Parliament.

"The Labour Right are showing once again that their priority is advancing the interests of their faction, not the wider interests of Labour or the people we seek to represent.

"This is why we should select principled candidates, who will fight for working class people, with a message of economic transformation and popular socialist policies our society desperately needs, replacing the current crop with grassroots activists and key workers."