Humza Yousaf says Kate Forbes and Ash Regan will 'lose SNP support'

In a plea to the undecided, Yousaf said he is the “only candidate who is ready to stand up to Westminster power grabs and solidify our pro-independence majority Government at Holyrood”.

Both Kate Forbes and Ash Regan have suggested that they would not challenge the UK Government’s use of a Section 35 order to block the Scottish Parliament’s gender reform bill.

Regan has also been critical of the governing agreement with the Scottish Greens, saying the SNP are "held hostage" by their coalition partners.

READ MORE: Humza Yousaf contradicts Alex Salmond's 'spoken to all candidates' claim

Forbes has been more supportive of the deal between the two parties, but reports suggest that gender reform could be a red line and that the Greens may pull out if the Section 35 order is not challenged.

In his open letter to members, which follows a similar pitch from Forbes which was published over the weekend, Yousaf writes: “While leaders change, what we stand for as a progressive, social democratic party, committed to fairness, respect, and equality does not.

“Now is the time to drive forward, with total commitment and conviction, our vision of the Scotland I know we can build with independence.

“As your SNP leader, I will never give up, or water down, that commitment to a fair, equal, and inclusive Scotland.”

He later adds: “I’m the only candidate who can lead from the front and offer the SNP the stability, unity, and strength in leadership that is so important at this time.

“As well as growing our support, we must have a leader who will not lose our party support. We know the vast, overwhelming majority of our members believe in a progressive, socially just Scotland, that is the Scotland I want to lead.”

SNP members have until noon on Monday March 27 to vote for their preferred candidate to take over as party leader from Nicola Sturgeon. The announcement of the winner is expected to follow soon after, once the candidates have been told.

In her pitch to the undecided, Forbes said that she had built her campaign “on the importance of honesty, integrity and reform”.

She said the SNP needed a change in both “culture and in policies”, writing: “If anyone was in any doubt that this needs to be a change election for the SNP, recent events and resignations confirm the core message of my campaign: continuity won’t cut it.”

Regan has also pitched herself as “the candidate for change”. She said earlier in her leadership campaign: “The SNP has been an electoral success for a really long time.

"I think we all recognise it’s been very successful. It’s had some really great policies, it’s done really good work for the people of Scotland.

“I would say, however, the SNP needs a new direction. I think we need to reprioritise in certain areas, and I think we need to bring unity back to the party.”