Kim Beazley says the dirt that's likely to be dished up in Peter Costello's memoirs will kill any chance of him being crowned Liberal leader.
The former Labor leader says Mr Costello, as the architect of the Coalition's economic policy for 12 years, would also be too easy a target for the government.
"If he does come back it will help discipline the Labor party's narrative about the past and that will assist them in disciplining their narrative about the future," he told Sky News.
"Costello, if he replaces Nelson, will be an easy target. But they'll have to direct the same criticism to Nelson himself while he's opposition leader.
"Opposition leaders always have a tough time - that's their life. I can't say I feel excessive amounts of sympathy for him, I went through it myself."
Mr Costello has said he will announce details about his future once his memoirs are published.
His silence on the leadership issue has seen current Liberal leader Brendan Nelson under mounting pressure.
Audio excerpt: Sky News