Prescott refused to appear at rally with Dobson

Frank Dobson's campaign for the London mayoralty suffered a fresh setback yesterday with the disclosure that John Prescott had refused to share a platform with him.

The Deputy Prime Minister shocked Labour officials when he bluntly turned down their pleas for him to appear alongside Mr Dobson and Tony Blair at a party rally last month. His refusal scuppered plans to give the prime ministerial seal of approval to Mr Dobson's campaign in the final stages of his Labour selection fight against Ken Livingstone.

The former health secretary had been lined up to appear for the first time with Mr Blair and Mr Prescott at a rally in west London, the last and biggest of a series of meetings with party members. But party insiders have said that the Deputy Prime Minister balked at the idea and threatened to pull out of the event if Labour's Millbank headquarters insisted on putting Mr Dobson on the platform.

A senior Labour source said yesterday: "John Prescott would simply not do it with Frank. Rather than go ahead without John, it was decided to do it without Frank. Frank was left grinding his teeth and pulling his remaining hair out."

Mr Prescott has always made clear that he would have preferred either Nick Raynsford or Glenda Jackson, both of whom were loyal ministers in his Department of the Environment, Transport and the Regions. Mr Raynsford, who lauched his own campaign during the Labour Party conference, was assured by Mr Dobson he would not run. Yet within days, Mr Dobson had declared and Mr Raynsford was forced to quit and back him.

The Deputy Prime Minister is understood to have insisted the appearance of Mr Dobson at the question-and-answer session with London party members would have been unfair to the other candidates. Mr Dobson was furious at the snub and Mr Blair had to pacify him with a photocall the day after the meeting. Mo Mowlam was also drafted in for the photo opportunity to stem stories suggesting she would replace him as a candidate.

The revelation follows speculation that the leadership is convinced of a victory by Ken Livingstone and is deserting Mr Dobson ahead of the May election. Despite pleas from the official Labour candidate, Mr Blair has so far refused to get actively involved in backing him. "Frank does feel let down. He doesn't feel the leadership is supporting him enough," said one ally.

Downing Street said this week that the Prime Minister would not take a high-profile role in the mayoral campaign, but insisted he would appear at some point with Mr Dobson. Mr Blair still has no dates in his diary for a joint appearance.

News of Mr Prescott's snub again distracted attention yesterday from Mr Dobson's attempts to focus on policy issues. He claimed Mr Livingstone's bond-issue plan for the Tube would cost Londoners £2.3bn.

Mr Livingstone launched his official campaign logo, "Ken 4 London", and campaign colour, purple - the one favoured by Roman emperors. The mayoral battle will hot up next week when nomination papers are submitted and manifestos likely to be announced by the main candidates.

Labour launched a new attack on Mr Livingstone's finances when an MP complained to the Parliamentary Commissioner for Standards that he had failed to declare his links with two after-dinner speaking agencies.