Labour are to announce who has won the battle to become the party's fifth leader in Scotland since devolution began in 1999.
Whoever wins the contest will take over a party still struggling to find way of taking on SNP First Minster Alex Salmond in Scotland at a time when Gordon Brown is enduring dismal poll ratings south of the border.
All three candidates are former Holyrood ministers - Cathy Jamieson, former justice minister and deputy Scottish Labour leader for the last seven years, former finance minister Iain Gray, and former health minister Andy Kerr.
The race is too close to call, but appears to be neck and neck between Ms Jamieson and Mr Gray.
Ms Jamieson, 51, comes from a left-wing background and is a former social worker who became deputy leader of the party in Scotland when Henry McLeish succeeded Donald Dewar.
Mr Gray, also 51, served as enterprise minister in the first Scottish Parliament, lost his seat to the Tories in 2003, but returned to Holyrood in 2007 as MSP for East Lothian.
Mr Kerr 46, served as finance minister and health minister, in which role he brought in Scotland's ground-breaking ban on smoking in enclosed public places in 2006.
The vacancy they are seeking to fill was created when Wendy Alexander quit in June after being found guilty of breaking Holyrood rules on declaring donations to her leadership campaign.
She had been leader for less than a year, succeeding Jack McConnell who stood down in 2007 after the Holyrood elections which saw Labour defeated by the SNP.
