HUMZA Yousaf leads in the latest poll of SNP members' voting preferences for the party's leadership contest.

A new survey of SNP members from Savanta ComRes puts Yousaf on 31%, Kate Forbes on 25% and Ash Regan on 11%.

Some 32% are undecided but with don't knows excluded, the results show Yousaf on 46%, Forbes on 37% and Regan on 17%.

Some 515 SNP members were polled for The Telegraph from February 23 to March 1.

In the last poll of SNP voters' preferences, from The BIG Partnership, 31% were undecided over who they want to see as Nicola Sturgeon’s successor.

Finance Secretary Forbes was in the lead, on 28% - followed by Yousaf on 20% and Regan on 7%.

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Chris Hopkins, director at Savanta, said: “This first poll of SNP members really indicates that the race to replace Nicola Sturgeon is too close to call."

He went on: “While Humza Yousaf narrowly leads Kate Forbes, with such a high proportion of undecided voters, it’s difficult to be able to say definitively who is really in the lead.”

“This is a unique first look at what actual members who can vote in this leadership election think, rather than polls of SNP voters who do not have a say in electing the leader.”  

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Neil Gray, one of Yousaf's backers, welcomed the poll, saying it shows he's "first choice for first minister amongst grassroots SNP members"

“With over three weeks to go, there is no room for complacency," he went on.

"Humza will continue to engage with our grassroots support, building the team to deliver on his progressive vision for a socially just, fair, and prosperous independent Scotland.”

Meanwhile, a spokesperson for Forbes told The Telegraph: “Whilst this is only a small sample, it does show that a number of people are still to make their minds up and Kate looks forward to making a positive case for her leadership bid at the hustings between now and the vote.”

Regan's team added that there are “a good number of hustings and debates until polling opens”, giving her more time to win over voters.

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How does the voting system work?

About 100,000 SNP members will be able to begin voting for their preferred candidate on March 13. Voting closes at noon on March 27 and the result is expected later that day.

SNP members will be asked to rank all three candidates by preference using a system known as the single transferable vote (STV).

First preference votes are then calculated and the third place candidate is disqualified if no candidate reaches 50% plus one of the vote.

The National:

The system then adds the second preference votes for either of the two remaining candidates to their totals, which should take one candidate to a majority.

However, depending who is eliminated after the first round, it could place the frontrunner at a disadvantage.

If, for example, Regan or Forbes lost at the first round, their supporters are more likely to have given their second preference vote to the other candidate due to their similar opposition to the Gender Recognition Reform (Scotland) Act.

This could place Yousaf in a tricky position – even if he had more first preference votes.