As Paul Kelly, the sober elder statesman of Australian political commentary, noted on The Australian newspaper website, the Gillard-Rudd argument is a contest of 'unparalleled ferocity'.

There are two reasons for this. One, it is a political fight to the death between two controversial politicians with arguably little to lose.

They carry little of the stature, or the mutual respect, of their predecessors Bob Hawke and Paul Keating during the latter's leadership challenge in 1991.

Keating, in a strategy that Rudd looks set to follow, launched a two-challenge bid. Then prime minister Hawke's treasurer, he lost the first battle and re-treated from Cabinet to the parliamentary back-benches.

Bloodied but not broken, Keating was free to rally the support and ammunition for a successful attack a few months later as the election loomed.

Hawke, of course, was a giant on the Australian political stage who had been in power for eight years, winning four elections.

Gillard boasts no such political strength or public popularity.

Her strategy, then, appears to be to deliver a fatal blow to Rudd - one that ensures he will never recover.

Her statements reflect her winner-takes-all effort ahead of tomorrow's snap leadership vote.

'I have formed this view that we need a leadership ballot in order to settle this question once and for all. For far too long, we have seen squabbling within the Labor Party. Australians are rightly sick of this and they want it brought to an end.'

Comments from her cabinet backers have been even more telling. Her treasurer, Wayne Swan, has attacked Rudd's leadership style and character, branding him selfish and 'dysfunctional'.

Swan said the party had given Rudd every opportunity, but he wasted them with his 'dysfunctional decision-making and his deeply demeaning attitude towards other people, including our caucus colleagues'.

Rudd, he added, had placed his own interests ahead of the party's.

'The Labor Party is not about a person, it's about a purpose. That's something ... Gillard has always known in her heart but something ... Rudd has never understood,' Swan said in what analysts described as one of the most stinging attacks in modern Australian political history.

Like the best political propaganda, it contains elements of truth, say those familiar with Rudd. Which leads to the second reason the fight is proving so vicious - and this is the strange personality of Kevin Rudd.

A Putonghua-speaking Sino-phile, Rudd is a former diplomat and Labor state bureaucrat. But for all the intellect and all the polish honed in the staterooms of Canberra, Stockholm and Beijing, stories of Rudd's tantrums are legion. YouTube viewers got a glimpse of his darker side last week when a recording of Rudd raging after a translator fluffed a word was leaked onto the internet.

Rudd refers repeatedly to 'this f****** language' and the 'd***heads at the embassy'. Then, in full diva mode, he tells an aide to cancel a 6pm meeting, saying he didn't have the 'f****** patience'.

Such incidents speak to Rudd's highly individualistic approach as prime minister. Avoiding or even ignoring his party's network of factions and cliques, Rudd became ever more distant from his own caucus and even his cabinet.

As he tried to push through with a highly-contentious tax on mining - a key Australian industry - the party's union supporters were outraged at a lack of consultation. Amid the internal turmoil, Gillard made her move.

Party insiders and some commentators are keen to put Swan's savage outburst into this context.

Gillard and her supporters were far too polite to Rudd following the coup, the thinking goes, despite reservations about the dangers of his isolationist style. As independent commentator David Marr wrote in the Sydney Morning Herald: 'No Kevin. This isn't a breakdown in civility. Your colleagues are at last telling us why you were sacked. And here the political is inescapably personal: you couldn't run the place.'

Certainly many outsiders who meet Rudd walk away scratching their heads. On the one hand, they describe a politician who is bright, engaged and on-the-ball.

Yet they also describe a pride and a pomposity that is never far from the surface. 'He has retained the air of the precocious schoolboy he undoubtedly once was,' one East Asian envoy noted after meeting Rudd as foreign minister. 'But he's no fool. He's certainly on top of his brief.'

Others ponder about his use of jarring, old-style phrases. For all his bookish and technocratic image, or perhaps because of it, Rudd loves to wallow in outdated Australian-isms.

A free-wheeling chat about the region in private might see Rudd offer guests 'a grog' before lurching into talk of the 'Chi-coms' - cold war-era speak for Chinese communists - 'Ruskies' and 'Yanks'. In public, he has been known to use 'Fair shake of the sauce bottle,' - a reference to the much-vaunted Aussie 'fair go'.

Yet a fair go is exactly what many voters believe Rudd hasn't had - and this will be a key feature of his plan of attack this weekend. While Gillard may have the votes of a majority of Labor MPs, Rudd is more popular with the public. And that is where the next election will be won.

As he formally announced his challenge on Friday, Rudd spoke of a lingering mandate. 'I want to finish the job that the Australian people wanted me to do - and I was elected by them,' he said before running through his successes, such as keeping the economy out of recession and the formal apology to indigenous Australians.

Pointing to numbers showing his period in government to be far more popular than Gillard's, he turned the argument to opposition leader Tony Abbott, reminding his party that he was the real enemy - and one who would have to be faced next year.

'This is the single most negative force in Australian politics - a person whose views lie right at the extreme,' he said of Abbott.

Rudd, too, has a compelling political story that continues to resonate with voters. His mother struggled after the death of his farmer father in Queensland - events that played a part in his political awakening.

He once described himself as a 'kid who lived [then-prime minister] Gough Whitlam's dream that every child should have a desk with a lamp on it where he or she could study.

'A kid whose mum told him after the 1972 election that it might just now be possible for the likes of him to go to university.

'A kid from the country of no particularly means and of no political pedigree who could therefore dream that one day he could make a contribution to our national political life.'

For all his success, Rudd's struggle is reaching its apex - the 'kid from the country' is now in the fight of his political life.