JOHN Swinney yesterday said he felt utterly liberated after deciding to stand down as leader of the Scottish National party.

Looking relaxed after the weekly meeting of SNP MSPs, he joked with reporters and spoke of the relief he felt when he made up his mind after a turbulent weekend. He said: ''The moment I decided on Monday the burden lifted spontaneously.''

He added: ''There were many warm tributes paid (at the meeting) and there was a realisation within the group, expressed across the board, that they have got to deliver a more united and cohesive approach than they have done to date.''

He also ruled out serving in his successor's shadow cabinet. ''What I did say is that I would not sit on the front bench, but a place on a committee would probably do. I was rather good at that in the old days.''

He added that his speech to the SNP national council in Stirling on Saturday, his last to the party as leader, would be from the heart, although whether this meant it would be friendly or contain payback for his enemies was unclear.

Because of his recent reforms to the way the party chooses its leaders - through one member one vote instead of branch delegates - he said his successor would be elected with ''an utterly commanding electoral base''. He said: ''You really can't quibble with that.''

His comments came as Nicola Sturgeon and Fergus Ewing emerged as likely contenders in the leadership contest. Most potential rivals to Roseanna Cunningham, the deputy leader and favourite to take over the party, are waiting to test the water in Stirling this weekend, when about 300 delegates will turn up for the party's national council.

Ms Cunningham was confirmed as the bookies' favourite yesterday, after William Hill quoted odds of 1/3 on her to win. Ms Sturgeon was second favourite on 3/1, followed by Alex Neil on 9/1, Fergus Ewing on 10/1, Alex Salmond on 12/1, Kenny MacAskill on 40/1, and Mike Russell on 50/1.

In what could be a bad omen for Ms Sturgeon, Sandra White, nationalist MSP, gave public backing to Ms Cunningham. Ms White, who topped the Glasgow regional list of SNP candidates last year, outranking Ms Sturgeon, said she would be likely to back Ms Cunningham.

''I believe Roseanna could be a unifying influence and would have independence at the very top of her agenda,'' she told the Evening Times, The Herald's sister paper. ''Of the names I have heard so far, she would be a front runner, and it is time for a woman to lead the party.''

Ms Cunningham began setting out her stall yesterday, promising a sharper campaigning edge for the party. The 52-year-old, a lawyer who was educated in Australia, told BBC Radio Scotland: ''I did not travel 12,000 miles back from Australia in order to fight for devolution and finish it there.''

She denied that she had been too quick off the mark in declaring her candidature, saying: ''I had made up my mind, I saw little value in being coy about it unnecessarily.''

She said she would have been doing colleagues a disservice if she had not made clear to them that her current post of deputy leader would be vacant as well as that of the leadership.

Most observers have argued the challenges facing the SNP run deeper than the question of who leads them, and that the party has lost its sense of direction under devolution.

Ms Cunningham appeared to accept this, saying: ''I think that's probably right. ''I have said all along that it isn't just about changing the face at the top, I think it's about focusing far more clearly on what the SNP's strengths are.''