Alastair Campbell discussed leaving Downing Street to work for News International with the then-chairman of the company, Les Hinton, at the height of the media furore over the suicide of Dr David Kelly in July 2003,
The revelation comes in the former spin-doctor's latest volumes of his diaries, The Burden of Power: Countdown to Iraq which covers the period from 2001 to August 2003, when Campbell left Downing Street.
Dr Kelly, a MoD expert, killed himself in July 2003 after being revealed as the source of a BBC story denied by the government that Campbell had "sexed-up" a dossier making the case to go for war in Iraq.
In the uproar that followed, Campbell revealed his partner, Fiona Miller, received letters asking "what is it like sleeping with a murderer". Campbell also received letters with fake blood in the envelopes. His sister Liz was also "getting abusive phone calls," according to an entry in July 2003.
The News International meeting at Hinton's house happened on 25 July 2003.
"Though I didn't go into timings I told him [Hinton] I would not be there [in Number 10] much longer. We discussed a few options with News International."
He notes in the introduction to the fourth volume of his diaries that he thought of suicide during the aftermath, writing that while driving: "I had one of those momentary reflections that life might be easier all round if I just careered off the motorway."
Campbell also dined with Rebekah Brooks [then Wade] and her partner at the time, Ross Kemp, in July 2003, where he discussed options to work for News International.
"TB [Tony Blair] felt the Sunday Times was the paper to do a column in. PG [Philip Gould] felt The Sun."
The death of government scientist Kelly was so traumatic for Campbell that he will never return full-time to front line politics, he says.
After Kelly's body was found on 18 July 2003 he was sent a message by then Sun editor Wade, which Campbell summarises as saying "you've done nothing wrong, told the truth, more principles than these other people." He says Piers Morgan, the then Mirror editor, was also "not totally unsympathetic."
He reveals in May 2003, prior to Kelly's death, that Hinton was the first person outside Campbell's "immediate circle" he informed that he was thinking of leaving.
"He started to go over the sort of things they might ask me to do, columns in The Sun and The Times, books, speeches etc.," Campbell writes.
Current Labour leader Ed Miliband told the Leveson inquiry earlier this month that Labour had been "too close" to Murdoch.
The diaries also reveal how Tony Blair likened Iraq to the furore over Foot and Mouth disease in May 2003. Campbell writes the then prime minister "said it reminded him of FMD [foot and mouth disease] before we gripped it and the military sorted it."
Campbell also discusses a phone call from Murdoch to Blair just before the beginning of the Iraq war on 11 March 2003, writing the mogul was "pressing on timings, saying how News International would support us."
On 20 March 2003 Campbell reveals that "preparatory action" in Iraq had taken the Ministry of Defence and most of the staff in Number 10 "totally by surprise." He notes that Blair and his aide David Manning knew but "neither thought to pass it on."
The Burden of Power: Countdown to Iraq is published in hardback and ebook by Hutchinson.