Labour's policy chief has hit out at the leadership for parking bold reforms in favour of "cynical nuggets of policy" designed to appeal to the press and focus groups.
Jon Cruddas has warned that the top of the party wields a "profound dead hand at the centre" that blocks plans, according to the Sunday Times.
A recording of the head of the party's policy review made at a meeting of the left-wing Compass group captured him attacking recently announced Labour plans to cut Jobseeker's Allowance for 18 to 21-year-olds as "punitive".
Mr Cruddas warned the "clock is ticking" but raised fears that interesting ideas were "not going to emerge through Labour's policy review".
It comes as Labour prepares to set out its vision for rebuilding Britain through major reforms of the state and big business in a series of events over the next week.
The party will reverse a century of centralisation by diverting £30 billion of funding to create "powerhouse" English cities and counties, Ed Miliband has said.
As well as pulling together plans on tackling "broken markets", changes to the welfare system and a crackdown on tax avoidance, it will lay out the results of former transport secretary Lord Adonis's review on growth polices.
Labour is already committed to increasing devolution of powers over housing, transport and skills to English cities and regions but is now setting the amount of cash it would transfer from Whitehall to £30 billion over the course of five years.
Party sources said the plans were a "determined and resolute break with the past" - not just with the actions of the Coalition Government but the previous Labour administration as well.
In an article for the Sunday Times, Mr Miliband wrote: "I am clear that our answer must be different in both scale and substance to the reheated 30-year-old ideology offered by this Government while going well beyond the solutions offered by the last.
"In their place I am setting out a new agenda for change in both markets and the state: a One Nation Labour plan for British people and British business to succeed together.
"Labour is developing a programme suited to these post-Crash times when spending or borrowing solutions are neither available nor adequate to deal with the challenges ahead."
He added: "The scale of the challenge means the next government must begin also begin reversing a century of centralisation.
"This week I will unveil Andrew Adonis's report on growth which recommends transferring £30 billion of funding to new powerhouse city and county regions over the course of the next parliament.
"This is just one of many ideas he has to nurture skills, help small businesses thrive and ensure innovation can flourish.
"It is a plan to mend fractures in our economy which have laid untreated for too long.
"We will not only hand power back from Whitehall we will change the way Whitehall works with the creation of a Small Business Administration in the heart of government to ensure fully a quarter of government contracts go to the dynamic small and medium sized firms that are our economy's future."
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