Gordon Brown would "probably" like to return to "the management of the international economy," a former aide told Good Morning Britain.
Damian McBride worked for the former Prime Minister from 2005-2009 and said Mr Brown had a "grasp of all of the global economic issues".
Damian McBride, who was forced to resign as former prime minister Gordon Brown's adviser in 2009 after being linked to a plot to smear Tory MPs on a gossip website, said:
The former spin doctor urged Labour to acknowledge its mistakes in government and to better communicate a coherent plan for the country. He wrote:
The Labour Party is being run in a "totally dysfunctional" way with policies that amount to "a great steaming pile of fudge", according to a former party spin doctor.
In an apparent attack on Ed Miliband's leadership, Damian McBride warned that the party has a problem in communicating positive messages to voters and that its policies either do not stand up to scrutiny or "go unnoticed in the pub".
In an updated version of his memoirs, serialised in the Daily Mail, Mr McBride said Mr Miliband should position himself as an outsider like Boris Johnson or Nigel Farage rather than an establishment politician directed by PR advisers.
Gordon Brown was warned about taking controversial spin doctor Damian McBride with him from the Treasury when he became Prime Minister, a former Cabinet secretary has said.
Lord O'Donnell said the incoming Prime Minister chose to ignore his advice in 2007, which he now believed had been "damaging" to Mr Brown.
Lord O'Donnell, who was speaking at an event at the Cheltenham Literature Festival, said Mr McBride had "gone off the territory" - even as a civil servant.
"I advised Gordon Brown when he was coming across to No, 10 not to take Damian with him and he chose to. Again I think that was damaging for Gordon Brown," he said.
Iain Dale, the publisher of Gordon Brown spin Damian McBride's memoirs and political blogger, has accepted a police caution for assaulting a protester as Mr McBride was being interviewed by Daybreak.
In a statement on his site, he has apologised for his actions:
Damian McBride has insisted that Labou leader Ed Miliband and shadow Chancellor Ed Balls knew nothing of his toxic briefings against other cabinet members.
He told ITV News' Deputy Political Editor Chris Ship that it "would have taken something of a criminologist" to trace some of the stories he was planting in the press back to him.
He also alleges that Downing Street advisers in "Miliband's camp" briefed against Balls during Gordon Brown's last days as prime minister.
A leading Catholic charity is facing calls to cut all ties with Damian McBride's explosive new memoir on the basis that it will "affect the charity's relationship with key political figures".
McBride is the head of media for the Catholic Agency for Overseas Development (CAFOD) and, according to his publisher Iain Dale, has agreed to donate some of his royalties to the charity.
A Twitter spat has now broken out between the editor of Catholic magazine The Tablet, who is calling for CAFOD to "disassociate" from these royalties, and Mr Dale:
Damian McBride compared his activities as Gordon Brown's spin doctor to those of a "rogue trader in the 1980s", saying Labour leaders were unaware of the way he operated.
McBride told ITV's Daybreak: "I'd compare it to when we had some of the rogue bankers ... people weren't asking enough questions about how they were making their profits."
Harriet Harman has denied that the Labour Party conference is being overshadowed by Damian McBride's book.
Speaking to Daybreak, the Deputy Leader said that in fact most people have never heard of the former Labour spin doctor.
Harman also said that the sorts of practices McBride claims to have undertaken do not occur in today's Labour Party:
She said: "Ed Miliband doesn't do that sort of thing, and doesn't allow anybody who works for him to behave like that."
Former Labour spin doctor Damian McBride has denied his controversial memoirs will damage the election ambitions of Ed Miliband, saying the party leader comes out well in his book Power Trip.
"I don't think this will make any difference to the way people vote at the next election," McBride told ITV's Daybreak, saying Miliband and shadow chancellor Ed Balls were "not involved" in any of his activities while he worked for Gordon Brown.
"I make no excuses for my behaviour and don't expect anyone else to," added McBride, who said he had operated in a political system that was "unacceptable" and "cut-throat".