Hostilities have resumed between the Blair and Brown camps despite Labour's attempt to portray a united front at its Manchester conference.
Allies of Gordon Brown accused Blairites of "character assassination" as it emerged Labour's private polling suggested the Chancellor was too closely associated with the Blair regime to offer the "fresh start" voters wanted.
His opponents say Mr Brown is seen as a figure of the past, not the future, who should depart with Mr Blair. He is also blamed by about 80 per cent of people for the attempted coup against Mr Blair three weeks ago. Although Mr Brown remains the front-runner to become the next Labour leader, some Blairites believe another cabinet minister may seriously challenge him if his poll ratings continue to slide. "The only thing that can stop Gordon is the public," one Blair ally said.
But Brownites said the Labour torch was already passing to Mr Brown after he intervened to save the party leadership from two embarrassing defeats when Labour's national executive committee (NEC) discussed whether to back a conference motion attacking the Government's health reforms and trade union demands for company bosses guilty of corporate manslaughter to face 14 years in jail. Both proposals were defeated by 16 votes to 15.
While Mr Blair remained silent, Mr Brown told the meeting: "The NEC must show leadership. We must demonstrate to the conference and the country we are serious and unified." He dismissed the union proposal on corporate manslaughter as "crazy".
The Brown camp is furious that ultra-Blairites appear to be undermining the Chancellor in the hope of creating an opportunity for a rival candidate. "They are playing a dangerous game," said one Brown ally. "If Gordon still wins the leadership, then the only person who will profit is David Cameron."
There is continuing tension over when Mr Blair should resign. Brownites are irritated by Mr Blair's move to exploit the rapturous reception to his conference speech by staying on until July. They hope he will leave by mid-June at the latest to allow Mr Brown to launch his premiership and make an impact on the public before the summer holidays.
"We won't be able to take on the Tories until the leadership issue is settled. We can't afford to waste the best part of a year," said one Brownite minister.
But Alan Johnson, the Education Secretary and a possible leadership contender, said Mr Blair had "a lot more gigs to come" and could stay on longer than many people had expected. "I really think people now are saying, 'Tony, the date you step down is a matter for you and it would be crazy to name a date'," he said.
Ultra-Blairites hope to persuade David Miliband, the Environment Secretary, to run against Mr Brown, even though he is backing him for the leadership. They want to "skip a generation" to combat the threat from Mr Cameron. One scenario is for John Reid, the Home Secretary to mount a "kamikaze" challenge aimed at weakening Mr Brown without landing the crown but allowing Mr Miliband to come through to win. But Mr Miliband told BBC Radio 4: "I've made my position so clear on this... I think Gordon Brown will, and should, be the next prime minister."
Blair supporters warned Brownites not to try to push the Prime Minister out before he was ready, saying that the Chancellor would get the blame.
The Brownites said Labour would "not tolerate" moves to weaken the Chancellor's position. "Some people are trying to create a self-fulfilling prophecy," one said. "If Gordon is accused of plotting by his own side, then of course the public will believe the headlines." They insisted Mr Brown would improve his poll ratings once he became leader by adopting an inclusive approach, a new style of governing and policies combining continuity and change.Reuse content