It is understood that Brendan Nelson is trying to end the damaging speculation regarding the Liberal leadership issue. However, one source predicts that treasury spokesman Malcolm Turnbull has the numbers to take the top job. Mr Turnbull only narrowly lost the leadership to Dr Nelson last year, and his supporters are now counting numbers for him.

For whatever reasons, Brendan Nelson’s poll figures are dismal, his impact nowhere to be seen, and under his leadership, the Opposition is going backwards. Senior Liberals need to learn from history and not make the same mistake they made with Howard in 2006: someone needs to tell him that it is time to go.

Peter Costello fooled everybody and, perhaps in the end, he fooled himself. He was the perfect candidate for the highest office, possessing stature, brains, wit and projection. Yet Costello’s political character fell short of the requirements for the prime ministership in a conundrum that will be debated for many years.

Malcolm Turnbull has broken his silence on the Liberal leadership, declaring “Brendan Nelson is our leader” but failing to rule out a challenge. Returning to Parliament today amid the lingering controversy over Peter Costello’s memoirs, Mr Turnbull said it was not his practice to comment on the leadership.

It was one of the main topics of Australia’s national conversation for almost half the post-Cold War era: would John Howard hand the prime ministership to Peter Costello? Or would Costello challenge him for it? From September 1999, when Costello said he had only “another budget or two in me”, to November 2007, when the Liberals lost power, the Howard-Costello leadership tension was a staple of political discussion.

The situation in June 2006 is not unlike that which has played out during the past few weeks. The guessing game of whether Peter Costello would stay in politics or go, whether he would be a leadership candidate or whether he was simply preparing to launch his book, ‘The Costello Memoirs’, and resign, kept sucking oxygen from Brendan Nelson’s leadership. Even after a contracted interview yesterday, there was uncertainty about Mr. Costello’s intentions.

The former treasurer, who retired to the back bench after last year’s election loss, told Fairfax radio this morning he would not retire until he reached the stage where he felt he could not give politics his full devotion. He said there were issues in his Melbourne seat of Higgins that he wanted to address and that he had not made a decision about his future in politics. In addition, Mr. Costello did not rule out standing at the next federal election.

Peter Costello may well leave parliament soon and take a job outside politics. Alternatively, the addiction to politics that has driven him to the heights of federal politics, implementing policies as Treasurer for more than a decade and assailing his Labor opponents for 18 years may yet prevail. For so long as Costello remains on the backbench, it pays to heed history. And history records plenty of future leaders who prematurely write their political obituaries.

Both Costello and Hanson were third party figures who hijacked the national conversation early in the life of a new government. Costello did it by saying nothing; Hanson did it by saying things that had never been said before by federal politicians. Both became self-fulfilling sagas at around the same point in the cycle - after the new government had delivered its first budget.

In his keenly-awaited memoirs, the former treasurer says he knew “in his bones that the 2007 election was lost even before the first votes were counted - and he blames the loss entirely on John Howard’s reluctance to give him the leadership”. “We lost because we failed to renew,” Mr Costello writes. “We did not arrange the leadership transition.”