It is still possible for the Office for Budget Responsibility to give Labour's plans for the economy "tough, rigorous and independent" scrutiny, Ed Balls has claimed ahead of a Commons vote today.
The shadow chancellor said he had been told by OBR chairman Robert Chote that cross party agreement this month could allow the necessary changes to be made.
Labour wants its plans signed off ahead of the general election as they battle polling showing they are less trusted on the economy than the current team.
Chancellor George Osborne yesterday rebutted plans for any immediate change to the OBR, insisting it could damage the institution.
Labour has called an Opposition Day debate and vote in the Commons today in a bid to force the issue. The vote, which the Government is expected to win, will be called at around 7pm.
Writing on Politics Home ahead of the debate, Mr Balls said: "Over the last four years the Office for Budget Responsibility (OBR) has become an established part of the framework of British economic policy with broad-based and cross-party support.
"I believe now is the right time to enhance the role of the OBR to help restore trust in politics. So in an Opposition Day debate in the House of Commons today I will argue that the OBR should be allowed to independently audit every spending and tax measure in the manifestos of the main political parties.
"I want that tough, rigorous and independent scrutiny for Labour's election manifesto and I believe the Tories and Lib Dems should be willing to subject their manifestos to such an audit too.
"In tough times it's even more important that the policies of all the parties are properly costed and funded. People rightly want to know that the sums add up."
Mr Balls said his plan had the support of some Government MPs, including the Conservative chairman of the Treasury Select Committee Andrew Tyrie.
And he said back in 2010 when the OBR was first created, Mr Osborne was "interested" in the idea.
The shadow chancellor added: "Robert Chote has said cross-party agreement would be needed by the early summer to do this for next year's manifestos.
"He has told me that an in principle agreement would be needed by this end of this month, so it could still happen if MPs do the right thing today."