Supporters of Mr Livingstone accused the AEEU, a right-wing engineering union, of boosting the number of members it affiliates to the Greater London Labour Party to "buy" votes when the party chooses its candidate for mayor. The unions have one-third of the votes in the electoral college selecting Labour's candidate.
The AEEU, which has almost doubled the size of its affiliation in recent years, will command almost 4 per cent of the college and cast its votes for Mr Dobson.
Figures published in tomorrow's edition of Tribune show that the AEEU has increased its strength from 27,500 to 50,000 - against the trend in other unions at a time of falling membership. The left-wing Transport and General Workers' Union has cut its number of affiliated members from 120,000 to 50,000 and the GMB general union has reduced its strength from 92,000 to 70,000.
The AEEU dismissed as "absolute rubbish" the suggestion that its rise was connected with the mayoral race. It had been under-represented in the London party and so had affiliated more members last year - long before the electoral college was set up. A senior AEEU source said: "I am pleased our opponents afford us such far-sighted judgement, but in this instance it has nothing to do with anything other than adequate affiliations."
Mr Livingstone is expected to win a majority in the union section of the college, but Mr Dobson's minority share could help him to overall victory. Ministers' hopes that scrapping plans to allow Railtrack to take over part of the Tube would also take the wind out of Mr Livingstone's sails proved short-lived yesterday.
The Brent East MP, who strongly opposed the takeover, partly because of the Paddington train crash, claimed the credit for the U-turn - but demanded that the Government abandon its plans for Tube part- privatisation. "If this is what I can achieve in two weeks as a candidate, think of what I can do for London if I am mayor," said Mr Livingstone, who said the decision to drop the Railtrack scheme had been taken because Mr Dobson's campaign was "dead in the water".
Mr Livingstone predicted that John Prescott, the Deputy Prime Minister, would perform another U-turn next spring by scrapping the privatisation plan and backing his scheme to finance improvements to the Underground by issuing bonds.
Downing Street was drawn into the controversy over the future of the Tube when Tony Blair's official spokesman accused Mr Livingstone of seeking to "move the goalposts" after the Railtrack decision and "pull the wool" over the eyes of Londoners.
Although Mr Dobson welcomed the Government's retreat over Railtrack, Mr Prescott insisted his decision was taken on practical rather than political grounds. "Ken is running for election, I am having to deal with getting a better quality public transport system," he said.
Mr Prescott denied the Government was backing away from its plans to inject private capital into the Underground. "I am committed to the public- private partnership, it is indeed a manifesto commitment. That is what I am carrying out," he said.
Speaking at a road congestion conference yesterday in Millbank, London, Mr Livingstone described the city's public transport system as a "second- rate mode of transport". He said a main reason why people still took their cars into London was that the buses and trains were a nightmare. "We have got to see the reintroduction of conductors on double-decker buses in central London and improvement in cleanliness."
The bus used to be the mode of transport for all. "Now it is a second- rate mode of transport. The bus companies have to get their act together." He added that bus lanes need to be enforced properly.Reuse content