Labour chiefs are to step up the process of finding a new leader, after Jack McConnell stood down.
A meeting of the procedures committee is expected to arrange the initial stages of the selection process.
Paisley North MSP Wendy Alexander is the only confirmed runner for the top job.
At the same time, two other potential candidates, former health secretary Andy Kerr and Glasgow Bailieston MSP Margaret Curran, have announced they will step aside.
The only other realistic candidate appears to be deputy leader Cathy Jamieson.
One dark horse could be former social justice minister Iain Gray who returned to Holyrood at the May election, after a four year absence.
Any candidate would require only six of Labour's 46 MSPs at Holyrood to nominate them.
Ms Alexander's official campaign will kick off in Edinburgh. The former enterprise minister said yesterday: "We can use our time in opposition to reform and reorganise the party in Scotland and find new ideas to reconnect with the people of Scotland.
"It will be a big challenge but it is one I am willing to undertake if I win the backing of the Labour membership."
Mr McConnell's departure was followed by the news that he is to become the UK's next High Commissioner to Malawi, after accepting a nomination by Prime Minister Gordon Brown.
