Richard Leonard will focus on his loyalty to Jeremy Corbyn in his attempt to secure victory over Anas Sarwar as voting gets underway in the Scottish Labour leadership election. A messaging document written by his campaign chief, Danielle Rowley, to be sent to Leonard’s supporters later today and seen by the New Statesman, uses the repeated phrase “only one candidate” to lay out dividing lines against Sarwar, who is seen as being from the party’s centre.

“Only one candidate opposed the coup against Jeremy Corbyn – rather than supporting it,” the document says, adding: “If it had succeeded it would have been a disaster for Labour. Only one candidate respected the choice made by the party membership just one year before.”

In addition, the message plays up some of the controversies that have hit the Sarwar campaign, adding that “only one candidate has spent their political life fighting firms that don't pay the living wage”, and that “ only one candidate has promised to use the end of private schools’ exemption from non-domestic rates to pay for school trips for children currently missing out”. The Sarwar family firm was found not to pay the living wage while Sarwar’s own children attend private schools. In addition, the campaign will emphasise that only Leonard’s manifesto mentions climate change and pledges to introduce rent control.

A spokesperson for the Sarwar campaign hit back at the Leonard campaign, saying: “This is a desperate attack from the chair of a campaign that is increasingly panicked. We will continue to focus entirely on our positive campaign of progressive taxation, tackling child poverty and retaining membership of the EU single market.”