Left MP Katy Clark launch her bid to become Scottish Labour’s deputy leader on Saturday, and has already won the support of two unions.

Rail union TSSA and Unison gave their backing to the North Ayrshire MP along with MSP Neil Findlay for the party’s leadership.

TSSA general secretary Manuel Cortes said Ms Clark stands for a “workable alternative to the market-driven madness.”

And he said: “Labour won’t be able to win Scottish hearts and minds unless it ditches failed austerity and neoliberalism.”

Unison said Ms Clark’s views are “consistent with Labour’s traditions and values and that is vital if Scottish Labour is to build its support in Scotland.”

Ms Clark revealed she would stand in a statement on Saturday, saying the race was about principles not personalities.

“We must recognise that Scottish politics has changed and it can’t be business as usual,” she said.

“The vast majority of people want a secure job, a decent home and access to good-quality public services.

“These are the issues I will be addressing throughout the campaign.”

Ms Clark is expected to set out further details about her platform for the leadership today.

She faces a tough fight against MSP Kezia Dugdale, one of the few Scottish Labour figures to emerge from the independence referendum campaign more popular.

Many of the 11 MSPs and MPs supporting her campaign are also backing Jim Murphy for leader — drawing clear battle lines between the party’s left and right.

Ms Dugdale wrote on Twitter yesterday that she was “delighted” and will outline her position later this week.