In the latest instalment of his diaries, Alastair Campbell said relations between the pair “got so bad” that Mr Blair sounded out other EU leaders about becoming president of the European Commission.
The crunch point was reached in 2004, three years before Mr Blair eventually stood aside for the then chancellor.
Mr Blair only ditched the idea because he feared he was being driven out of office and realised “he had to stay and see it through”.
Mr Campbell’s diaries, being serialised in The New European, also reveal Mr Blair openly talked about resigning on the night of his third election victory in 2005, which saw Labour’s majority significantly reduced.
The diaries cover the period from 2003 to 2005, when Mr Campbell remained a confidant to Mr Blair despite resigning as communications chief over the Iraq war.
They give a further insight into the tensions and rivalries at the top of New Labour.
On Mr Blair’s plan to seek the European presidency in 2004, Mr Campbell writes: “A lot of the time the press exaggerated our difficulties.
“This was one period where, if anything, they underplayed them because they didn’t know just how bad things were.
“This was the closest Tony got to leaving and at the time I was terrified it would get out because it was one of those stories that would have taken on its own momentum.
“Tony had pretty much had enough and was being ground down by Gordon. In the end he realised that and decided he had to stay and see it though.
“Then came another on-off saga when he decided he was going to sack Gordon.”
Mr Campbell said it was “amazing” Mr Brown and Mr Blair were able to work together in the 2005 election, given the split.
News Source SkyNews