Richard Leonard pledges to emulate Jeremy Corbyn and breathe "new life" in to Scottish Labour

Mr Corbyn has spent three days north of the border, attending Labour’s National Executive Committee alongside Mr Leonard, as the party launched a weekend of national campaigning with activists on the streets across Scotland.

He will make clear he wants to work as “closely as possible” with the Central Scotland MSP to not only ensure Labour wins the next General Election and Holyrood election but also that their party is the largest at Westminster and Holyrood.

It is widely believed that Mr Corbyn and Kezia Dugdale, the former Scottish party leader, were not political soulmates; Ms Dugdale famously suggested she needed convincing the UK leader could be Prime Minister and backed his rivals in the leadership contests. In contrast, Mr Leonard, firmly on the Left of the party, was regarded as Mr Corbyn’s preferred candidate in his successful race against Centrist MSP Anas Sarwar.

Mr Leonard will use a keynote speech in Glasgow to say that the core of his leadership campaign will form the basis of Scottish Labour’s future programme for government.

He will say: “We must give our people the confidence that real change can happen. That’s the agenda I set out over these past few weeks…a plan for real change, that we must now take into our party and to the people of Scotland.”

Invoking the spirit of the party’s founder Keir Hardie, the new Scottish party leader will note how a “powerful mission can and must always be reshaped and recharged”.

He will say: “That’s what Jeremy Corbyn has done so successfully as leader of the party in Westminster. His principles, policies and integrity - along with the energy and passion of hundreds of thousands of new members - has breathed new life into our party. I pledge to do the same here in Scotland.”

In the run-up to the Scottish Labour conference in Dundee in March, Mr Leonard announced the establishment of 12 policy reviews and a commission on tax to further develop party policies on what he will say are the vital issues facing Scotland, including: funding and powers for local government; meeting the housing crisis challenge; improving children’s health; tackling climate change and developing green energy as well as extending public ownership.

“This moment can be a turning point for our party in Scotland but also for the UK as a whole,” he will declare. “We can and must change our society. We will challenge austerity from the SNP in Holyrood and the Tories in Westminster.

“Inequality, injustice and poverty are not inevitable. Together, we can seize the day and, as John Smith said when he became Labour leader: ‘persuade millions of the strength of our vision, the relevance of our policies and the urgency of our demand for change’”.

Mr Corbyn will offer his “warmest congratulations” to Mr Leonard in his victory for the Scottish Labour crown, saying his colleague will “once again bring hope and confidence to the people of Scotland”.

The UK party leader is due to say: “During this leadership election, Richard laid out a bold and radical agenda for Scottish Labour and showed his determination to bring real change to Scotland. I look forward to working as closely as possible with Richard to change our society for the many not the few.”

He will insist that the whole Labour movement must campaign together to “inspire people in every nation and region of the UK to have the confidence to be a country that genuinely cares for all”.

Mr Corbyn will add: “It is Labour that offers the Scottish people real change and a break with the failed and rigged system that has held our people back.

“Together with the people of every nation and region of the UK, we will build a new economy that delivers good jobs and cutting-edge investment in every part of our country and puts equality and social justice at the heart of everything that we do.”