Doubts are growing about Dr Mo Mowlam's survival in the British cabinet until the general election, following the latest accounts of the extent of her estrangement from the British Prime Minister, Mr Blair.
A biography of Dr Mowlam by Ms Julia Langdon, reveals how, feeling humiliated and frozen out during vital Northern Ireland negotiations, Dr Mowlam took revenge by refusing to take Mr Blair's telephone calls, and used "splendid invective" against him.
The book reveals Dr Mowlam once told President Clinton: "Didn't you know: I'm the new tea lady around here," - and was "crestfallen" when given the Northern Ireland job in 1997, thinking herself set for higher office. Downing Street had confirmed "the intention" that Dr Mowlam would retain her Cabinet Office post following last Monday's confirmation of her decision to stand down at the next election.
A source close to Mr Blair admitted the facade of unity would only be maintained only "with the utmost difficulty".
Impressions of personality faultlines at the very heart of the Labour government, meanwhile, are given further ammunition by a new book suggesting a bruising and continuing battle for authority between Mr Blair and the Chancellor, Mr Gordon Brown.
The book - Servants of the People, by the Observer's political commentator, Mr Andrew Rawnsley - claims regular raging arguments between the two which have threatened on occasion to derail the government's most important policies.
The latest airing of the tensions between 10 and 11 Downing Street will again threaten the New Labour image, two weeks before the party's conference.
Among the headline-catching claims in the book, serialisation of which began yesterday, are that the Chancellor:
threatened to resign earlier this year over a pro-euro speech by Mr Peter Mandelson;
wanted to sack the governor of the Bank of England immediately after the 1997 general election;
kept the prime minister in the dark about a fundamental change in policy on the euro in the same year;
rowed with Mr Blair over a pre-emptive commitment to raising health spending to the EU average, shouting: "You've stolen my f***ing budget."
The book claims Mr Blair once remarked: "Gordon's problem is that he hasn't got a family" - while revealing a Chancellor unimpressed with Mr Blair's economic competence, saying:
"Tony wants to tax less, spend more and borrow less. Our job is to make it add up for him."
The Scottish Secretary, Mr John Reid, however, insisted the cabinet was more "ideologically united" than any he had known. And Mr Peter Mandelson again dismissed claims he had briefed against Dr Mowlam as "rumours, rumours, rumours".
The author of the Mowlam biography, Ms Julia Langdon, told GMTV's Sunday Programme the former Northern Secretary had read her manuscript and made no changes. While Ms Mowlam had not authorised the book, Ms Langdon confirmed: "She said `I will let you talk to my friends and I will let my friends talk to you, if you let me see the book and change errors of fact'."
Mr Rawnsley, meanwhile, claims Dr Mowlam pitched for Defence as a stepping-stone to the Foreign Office during last year's reshuffle, and actually turned down the Department of Health because of a long-running feud with Mr Brown.