The Scottish National Party has been thrown into turmoil by the surprise announcement that a little-known party activist has launched a leadership challenge against John Swinney.
After the party's disappointing performance in the recent elections for the Scottish Parliament - when it lost eight of its 35 seats - Bill Wilson, a failed parliamentary candidate, said he wanted to give grass-roots supporters the chance to protest at the direction in which Mr Swinney had taken the party.
For months Mr Swinney has had to contend with sniping from within his own ranks about his lack of charisma compared to his predecessor, Alex Salmond.
There has been growing discontent in the rank and file of the party, with claims of infighting, control freakery, bullying and backstabbing within the leadership.
Dorothy-Grace Elder, a former MSP for the Scottish Nationalists who quit the party because of what she believed was "stupid, arrogant and bullying behaviour", said yesterday that there was a widespread feeling among ordinary party members that the grass roots had lost control of the SNP.
Her view was shared by Bill Taggart, a former party activist who left the SNP after 24 years to join the Scottish Socialist Party. "The party has gone down hill," he said. "It has lost its way and a lot of people are not happy. The leadership don't listen."
While Mr Wilson is not expected to win the challenge, he is seen as a stalking horse who could cause serious damage to Mr Swinney's credibility.
Roseanna Cunningham, the SNP's deputy leader, said: "This is a leadership candidate who is unknown. There has been some widespread discussion about a stalking horse candidate for a while."
She described the challenge as a "fake contest" and a "sideshow", but admitted there was an anti-Swinney faction within the party. "This is just designed to weaken and damage," she said.
Mr Wilson denied that he was a stalking horse. He said he was providing an opportunity for people to show their disappointment.
"This is an issue for the grassroots members," he said. "It's to give them a chance to speak out and say they are not happy with the direction of the party. I've had a lot of contact from grassroots members saying, 'Somebody please stand.' We want this party back to democracy; we don't want centralised control, we don't want New Labourisation."
Mr Swinney, who will defend his position against the challenge at the SNP's September conference in Inverness, accused Mr Wilson and his supporters of playing games. "I will contest this challenge vigorously to safeguard the future of the SNP," he said.
"The choice is between my leadership, which is about building the SNP into a strong and credible political force capable of defeating the Labour Party, or engaging in student politics that will delight the Labour Party. This is not a time for people to play games."