In a move that will embarrass the Labour leadership, the two candidates are to protest at the handing over of the party's list of London members to their rival Frank Dobson, who is Tony Blair's choice for the Labour nomination.
The complaint will be made to Unity Balloting Services, which is conducting the ballot for Labour and acts as the independent scrutineer. The company could order the contest to be re-run, and Mr Livingstone and Ms Jackson hope that it will at the very least order Labour's Millbank headquarters to hand over the membership list.
In separate letters to be sent on the same day, Mr Livingstone and Ms Jackson will ask Unity to investigate allegations in a BBC Panorama programme that Mr Dobson obtained the list with the help of senior officials at Millbank. Labour has denied the claims, and the Dobson camp insists the names were handed over by London Euro MPs.
Unity will be asked to probe claims by Mr Livingstone, writing in The Independent on Wednesday, that Mr Dobson has used telephone canvassing and mailshots while his two rivals have had to send material to local party secretaries to be passed on to members.
By already having the names and addresses of members, Mr Dobson would save pounds 6,000 on the two mailshots all candidates can send to the membership - a tenth of their spending limit for the campaign, Mr Livingstone said.
He added last night: "The selection of the Labour candidate for London Mayor must be seen to be fair. This must mean that all candidates have access to the membership list. This is currently far from the case." The left-wing Brent East MP also said Labour should ensure no candidate had special access to the list or that all candidates had the same access.
Mr Livingstone and Ms Jackson decided to make acomplaint after studying a transcript of Monday's Panorama programme. They are also furious at press briefings from the Dobson campaign, which has been reported as saying: "Any candidate who can't get hold of the list is obviously disadvantaged, but that's politics."
A source close to Ms Jackson said: "These remarks were the final straw. We know the selection is a stitch-up, but we will not sit back and have our noses rubbed in it too."
Tony Blair's handling of the mayoral selection was criticised by Neil Kinnock in an interview in the New Statesman magazine. Asked if he would have blocked Mr Livingstonefrom Labour's shortlist, Mr Kinnock said: "Put it this way. I think I would have had the argument much longer ago."
The Dobson campaign received a boost last night when Mo Mowlam, the Cabinet Office Minister, backed his bid. She said: "The London Mayor must be a serious candidate for a serious job. I have no doubt that Dobson is the only candidate with those qualities, uniting London, not dividing Labour."Reuse content