MALCOLM Turnbull has been a highly successful lawyer and businessman.
Australians now have the chance to discover if he can be a successful prime minister and revive the Liberal Party's fortunes to lead them to victory at the next election.
If he does, Turnbull will be following a fundamentally different approach from that of Tony Abbott. While Abbott, like John Howard before him, attempted to wedge off social conservatives from Labor's support base, Turnbull will partly attempt to attract current Labor voters who have relatively progressive social views but who see him as a better economic manager.
This is why, when he called on Monday afternoon for a leadership spill, Turnbull focused on Abbott and Treasurer Joe Hockey's economic failings.
A shift from social conservatism?
The great danger that Turnbull poses to Labor is precisely that he is a potential crossover candidate who is much liked by many Labor voters.
As his fateful decision to knight Prince Phillip revealed, Abbott often had to be dragged into the 21st century. The man who had hurled abuse at feminists as a young student activist slowly came to accept that the gender equality he had railed against was a widely accepted value in contemporary Australian society.
His wife even claimed he had become a feminist, although Abbott still not-too-subtly used Julia Gillard's gender against her.
The man who made appallingly homophobic remarks as a student eventually ended up publicly embracing his lesbian sister, even if he couldn't quite come so far as to allow her to marry.
Are you more likely to vote for the LNP under Malcolm Turnbull?
This poll ended on 22 September 2015.
Yes. He will lead a better government
No. It's still the same LNP
Depends on if policies are changed
I just think it's wrong they can change the leader
This is not a scientific poll. The results reflect only the opinions of those who chose to participate.
Perversely, what appeared to be a victory for Abbott's social conservatism might actually have contributed to his defeat.
The Coalition's rejection of a conscience vote on same-sex marriage and Abbott's subsequent mooted proposal to take the issue to a plebiscite or referendum in 2017 may have facilitated some conservative Liberals - who would otherwise have strongly opposed Turnbull given his views on same-sex marriage and a conscience vote - to support his leadership challenge on the assumption that he would now support the status quo.
If Abbott's problem was that he often seemed to be behind the times, Turnbull's is that he often seems to be slightly ahead of them - and that he can't always take either his partyroom or the public with him.
Turnbull recognised the importance of action on climate change, and the need to develop a 21st-century, low-carbon Australian economy relatively early.
However, the bipartisan emissions trading scheme he successfully negotiated in 2009 fell victim to a mobilisation by Liberal Party climate change sceptics. His leadership of the party ended with it.
Unfortunately for Turnbull, Abbott's slogan depicting Labor's attempts to introduce a carbon price as a "great big new tax" captured the public's imagination in a way that Turnbull's carefully thought-out arguments in support of an emissions trading scheme did not.
Turnbull was a relatively successful communications minister, albeit while overseeing the introduction of an increasingly costly broadband program that is still much less ambitious than Labor's fibre-to-the-premises plan.
Australia's internet speed remains slow by international standards.
Abbott famously declared that he was not a "tech head" when bamboozled by relatively simple questions regarding the Liberals' broadband plans.
By contrast Turnbull literally made a fortune out of his involvement in IT businesses such as OzEmail. He now promises to help steer Australia through coming technological disruptions.
However, it is not just his grasp of climate change and technology in which Turnbull has proven to be arguably more in tune with the 21st century than Abbott is.
He has also made some important statements regarding the challenges which the rise of key Asian economies poses for high-wage, first-world economies with extensive social welfare safety nets such as Australia.
Turnbull is well aware that the era of unquestioned Western dominance has ended, and that existing Australian living standards are under threat in the Asian century.
However, while Turnbull seems far more aware than Abbott was of the impact of changing geopolitics and geoeconomics, Turnbull's solutions still tend to be neoliberal ones.
He strongly supports free trade and opposes protectionism - hence his critique of Labor's questioning of aspects of the China free trade agreement.
Turnbull argues that government should play a relatively minimal role, tending to rely on improving education and training and governments leading by example in areas such as IT implementation.
Despite his progressive social values, Turnbull is relatively "dry" when it comes to economics.
He strongly criticised the Rudd government's Keynesian deficit spending programmes to counter the global financial crisis as being excessive.
So, in many respects, Turnbull seems an ideal Liberal leader for the 21st century. But there are some potential downsides.
Despite suggestions that he has learned from his previous mistakes when Liberal leader, Turnbull has been criticised for being arrogant and not consulting sufficiently - hence his reassuring claim in his acceptance speech that he will be "first among equals".
Opposition Leader Bill Shorten has already picked up on this weakness.
There are issues over whether Turnbull will be able to keep the Liberal Party and the Coalition united. Turnbull's values hark back to earlier periods of Liberal history when moderate, small "l" liberals had a more dominant role in the party. Right-wing opponents within the Coalition hate Turnbull's socially progressive views.
However, Turnbull's views on these issues are not as left wing as some Liberals and National Party MPs seem to believe. He previously only advocated a conscience vote - not binding policy - on same-sex marriage.
Conservative leaders such as David Cameron in Britain and John Key in New Zealand have also supported same-sex marriage being introduced in their countries. Cameron also takes issues of climate change extremely seriously.
It is often forgotten that Turnbull managed to win major transitional concessions for carbon-intensive industries when he negotiated an emissions trading scheme with the Rudd government. Turnbull has already suggested that he would feel bound for the current term by the Direct Action policy that the Liberals took to the election, despite having criticised it in the past.
Turnbull's judgement has also been called into question, especially after the Godwin Grech debacle during his previous period as leader.
Turnbull criticised the Rudd government for misleading parliament on the basis of spurious, doctored documents. He apparently naively overlooked the simple possibility that Grech could have changed the content of forwarded email messages.
Those who voted for Turnbull in the partyroom will be hoping that he has overcome such quirks and that he can bring both the partyroom and the public with him when he tells the voters sometimes uncomfortable truths about 21st-century Australia.
They will be hoping that his pledge to explain "challenges and opportunities" really is more successful than Abbott's slogans.
Howard and Robert Menzies resurrected their political careers and took the Liberals to victory after being ousted as party leader. We wait to see whether Turnbull can do the same
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