The battle for Glasgow East has begun, as the main parties begin their campaign.
Labour is expected to confirm who it will choose as its candidate today, while Tory Davena Rankin will begin her campaign.
Glasgow councillor John Mason will represent the SNP and maths teacher Ian Robertson the Liberal Democrats.
Former MSP Frances Curran will stand for the Scottish Socialist party.
The by-election was triggered by the sudden resignation of Labour man David Marshall on grounds of ill health.
Labour currently holds a 13,507 majority over the SNP but that fact could ultimately count against them at the by-election.
With the party's fortunes so low and those of the SNP very high, any loss here would be seen by politicians and journalists as an unrecoverable moment in modern Labour history, and would certainly provoke a torrent of speculation on Gordon Brown's position.