The architect of High Speed 2 and the head of Labour's growth review says that Ed Balls's threat to withdraw support for the project has "raised the bar".
A mass housebuilding programme designed to stimulate growth and employment, and limit price rises, could be the game-changer Labour so badly needs.
After months of rumours that he's set for the chop, the shadow work and pensions secretary threw blow after blow at the Tories.
Andrew Adonis, the head of Labour's growth review and the architect of the project, has warned that cancelling the programme would be an "act of national self-mutilation".
Osborne's instinct will be to use the extra revenue for faster deficit reduction or tax cuts. But Labour can argue for an alternative centred around investment.
The party says the proposal, reportedly considered by Jon Cruddas, is "not part of the policy review" after opponents label it a "jab tax".
Osborne is determined to claim that there is a "black hole" in Labour's spending plans, whatever the Office for Budget Responsibility may say.
Our pledge to provide all parents with access to childcare through their school from 8am-6pm will give men and women equal opportunity to succeed in the workplace.
A commitment to a mass housebuilding programme and plans to reduce energy price rises will be the centrepiece of his "cost of living" address.
Labour was founded as a party of action, taking on local landlords, bosses and racketeers. Today we are reshaping the party to honour that tradition.