David Miliband appealed to Tony Blair not to issue a public declaration of support in his battle to become the next Labour leader, fearing it could damage rather than boost his prospects in the contest, The Independent can reveal.
However Mr Blair still appeared to give his tacit support to Mr Miliband's bid as he warned his party it would consign itself to the political wilderness if it takes a left turn.
The Blair memoirs, A Journey, were published on the day ballot papers were sent out for the Labour leadership election and injected another factor into the race.
Candidates, including David Miliband, called for the party to "move on" from the Blair-Brown era as opponents of the shadow Foreign Secretary suggested that Mr Blair's return to the political spotlight could harm his one-time protégé and head of policy. Mr Blair endorses Alistair Darling's proposal to halve the public deficit over four years, which is supported by Mr Miliband, and says Labour must have a "coherent" and "credible" position on the deficit if it is to regain power.
But his book casts doubt on Mr Miliband's hunger for the leadership in 2007, when he declined to challenge Mr Brown after Mr Blair bowed out. "He was hesitant and I felt fundamentally uncertain as to whether he wanted it," he writes. Mr Blair told his former policy chief: "I think you might win, not obviously, but very possibly." He insists that Mr Miliband is now "a different calibre of politician, with clear leadership qualities".
Last night, Mr Blair told Andrew Marr in a BBC TV interview that Mr Miliband is "very much his own man". In an implicit rejection of his brother Ed's pitch, Mr Blair said Labour must "always be at the cutting edge of the future, it's got to be prepared to change and adapt, and that means on public services and welfare you cannot run them in 2010 as if you were still in 1950. And the question for the Labour Party is do you buck the historical trend, which has always been, you lose an election and then you go off and decide to lose a few more, before you come back".
Ed Miliband, his brother's closest rival in the race, said: "I think it is time to move on from Tony Blair and Gordon Brown and Peter Mandelson and to move on from the New Labour establishment. I think most members of the public will want us to turn the page."
David Miliband said: "I respect both Tony and Gordon deeply. But their time has passed. Their names do not appear on the leadership ballots. I'm sick and tired of the caricature that this leadership election is a choice between rejecting or retaining New Labour."
There was anger in the Brown camp at Mr Blair's criticism of his successor. Charlie Whelan, Mr Brown's former press secretary, said: "Needless to say, I won't be reading this trash. It's not true and Tony Blair knows it."