Former prime minister Julia Gillard has confirmed she urged Greg Combet to run as Labor leader in June last year, saying it became clear that her leadership "was very likely to come to an early end".
Launching Mr Combet's book in Sydney on Tuesday, Ms Gillard said she realised her leadership would not last until the federal election scheduled for September 2013, "despite the best efforts of her supporters".
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Speaking at the launch of Greg Combet's new book The Fights of My Life, former Prime Minister Julia Gillard confirms that she urged her colleague to run for the Labor leadership.
"There came a time when it was clear to me that my leadership was very likely to come to an early end," she said.
"My belief that the nation and my political party should be led by a person of good values and a clear sense of purpose remains strong...my view was that the best person at that time was Greg Combet.
"I wanted to see the next part of his life being for the support of his colleagues to lead the Labor government into the 2013 election but it was not to be.
"Now, Bill Shorten as Labor leader is taking his remarkable talents and fierce passion into the fight for fairness and a better future."
Last week while promoting the book, The Fights of My Life, the former climate change minister said he had turned down Ms Gillard's offer, in June last year, for him to take over as Labor leader and prime minister.
Asked about the revelation on Tuesday, Mr Shorten refused to comment, saying it was "water under the bridge".
Ms Gillard was joined at the launch by another former Labor prime minister, Bob Hawke.
Mr Combet said while writing a book can appear "conceited" he hoped he wouldn't be judged "too harshly" because he wanted to record the contributions of others to the Labor movement.
Meanwhile, Prime Minister Tony Abbott has defended Treasurer Joe Hockey over the Treasurer's new authorised biography.
Mr Abbott said Mr Hockey can't be blamed for the revelations stemming from contentious book, saying its content was in the hands of the author.
Not Your Average Joe, written by Fairfax columnist Madonna King has angered many Liberals, at least one of whom has described it as "unhelpful".
The book reveals Mr Hockey believed his first budget was too soft and also criticises the Treasurer's cabinet colleagues – Industry Minister Ian Macfarlane and Communications Minister Malcolm Turnbull.
But Mr Abbott backed his Treasurer on Tuesday saying the revelations are not his fault.
"I don't think we can blame Joe for that at all," he said.
"Once these projects get under way you're very much in the hands of the author."
Mr Abbott said he had not tried to stop Mr Hockey from cooperating because he was not in the business of trying to tell his colleagues to hide their "lights under bushels" and that it was difficult to stop people's intent on writing about you.
Mr Abbott said it was "perfectly understandable" that someone would want to write about the Treasurer because his story is a "great" one.
"Let's face it it's a great story," the Prime Minister told Macquarie Radio.
"The Hockey story is a great story – penniless migrants come to Australia from the Middle East and their son is now the treasurer of the commonwealth," he said.
But Mr Shorten renewed his attack on Mr Hockey.
"Joe Hockey obviously sees being Treasurer as a part-time job," the Labor Leader told reporters in Melbourne.
"The lesson here is when you're Treasurer of Australia, stick to your day job and leave the literary flights of fancy to people who are not as busy as you."
He said there was a "world of difference" between Mr Hockey's authorised biography which he described as a "job application" for the Liberal Leadership and Greg Combet's memoir, released on Tuesday, which looks back on his career as a union leader and Labor minister.