Former Foreign Secretary David Miliband has broken a long silence to warn that Labour needs "restless rethinking" if it is to return to power.
The South Shields MP says Labour must admit "loud and clear" where it got things wrong in power, but - in what may be seen as a defence of New Labour against his brother's criticisms - he insists the party must assert that the gains made between 1997 and 2010 "far outstripped the mistakes".
Mr Miliband praises his younger brother's leadership, but his decision to delineate his position on Labour's future direction will surely add fuel to speculation that he has not ruled out a return to the party's upper echelons.
Writing in this week's edition of the New Statesman, David Miliband says Ed should be given credit for preventing disunity in the Labour ranks since its disastrous 2010 general election defeat. And he says his brother has shown he understands the need for a policy rethink and has spoken "powerfully and correctly" about welfare.
But he warns there are elements within Labour who want to respond to defeat by retreating to "big state" social democracy.
And he says the party has "a lot to be concerned about" in terms of its prospects of electoral victory in 2015, when Conservatives will be boosted by their financial advantages and boundary changes which will favour them.
David Miliband wrote: "We will win again only when two conditions are met.
"First, that we fully understand in a deep way why the electorate voted against us in 2010. Second, that we clarify the kind of future we seek for Britain, and the means to achieve it, in a way that speaks to the demands of the time."
Labour must show they are "reformers of the state and not just its defenders.
"The weaknesses of the 'big society' should not blind us to the policy and political dead end of the 'Big State'.
"The public won't vote for the prescription that central government is the cure for all ills for the good reason that it isn't."
Mr Miliband's seven-point plan also included: balancing the aim of equality with an embrace of the ideas of merit, rights and responsibilities; support for devolution of power to local communities; "a politics of economic growth, not just redistribution and regulation"; and continued modernisation.
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