Both documents, due to be published this month, are said to detail a catalogue of criticisms of the operation of the beleaguered CPS. They present a direct challenge for the Attorney General, John Morris, who will decide the fate of Dame Barbara, and Westminster sources believe she is unlikely to stay in place for long.
Dame Barbara is believed to have applied for at least one job elsewhere. Even if she survives the publication of the reports, her contract, which expires next year, is certain not to be renewed.
Mr Morris, the most experienced minister in Mr Blair's government, was the object of criticism over the handling of the row at Christmas over cannabis possession by Jack Straw's son. Colleagues see this as an opportunity for him to redeem his reputation by acting decisively and moving more speedily.
One source said that Dame Barbara applied for the post of Permanent Secretary at the Lord Chancellor's Department but that position was filled last week by another senior civil servant.
The reports, by Sir Iain Glidewell and Gerald Butler, list errors of judgement going back over 10 years and describe a culture of mismanagement at the CPS. Draft copies are now in circulation in Whitehall and are said to have caused surprise at the extent of their criticisms.
They present Dame Barbara with a tactical problem: whether to argue internally that she is the person to sort out the problems catalogued, or whether to dispute the findings, even by taking legal action.
Sir Iain's document looks at the overall performance of the service while Judge Butler's inquiry was set up last year following the refusal of the CPS to proceed against police officers involved in the deaths of two people in custody.
But in recent years there has been a steady stream of criticism against the CPS concerning its failure to prosecute in controversial cases and the collapse of some high profile court actions.
Large-scale changes in the way the CPS operates have been put on ice until after the Glidewell report. But Mr Morris has already indicated that he wants to replace its bureaucratic, top-heavy organisation with a localised system headed by powerful chief crown prosecutors.
He is expected to establish at least 30 regional prosecutors to whom most of the current powers held by headquarters staff will be devolved.
At present the 13 regional offices are run as outposts of CPS headquarters, rather than as independent prosecution departments with their own powers of decision-making. But, critics argue, that has swamped headquarters staff in paperwork.
Earlier this year Mr Morris said the service had moved away from the original concept, laid down by Sir Leon Brittan 10 years ago, and had over-centralised. There were, Mr Morris added, "not enough resources being used to ensure that lawyers, as opposed to the bureaucratic part of the machinery, were being used to best advantage".Reuse content