However, his support of the Carbon Pollution Reduction Scheme proposed by the Rudd government in December 2009 led in turn to a leadership challenge by Tony Abbott, who defeated Turnbull by a single vote.

Though initially planning to leave politics after this, Turnbull chose to remain and was later appointed Minister for Communications in the Abbott government following the Liberal-National Coalition's victory at the 2013 election.

Two years later, citing consistently poor opinion polling, Turnbull resigned from the Cabinet on 14 September 2015 and challenged Abbott, successfully reclaiming the leadership of the Liberal Party by ten votes.

The Turnbull government initiated the National Innovation and Science Agenda as its key economic priority, working to promote STEM education, increase venture capital funding for new start-ups, and launch an "ideas boom".

[1] Turnbull also pursued "city deals" with local and state governments to improve planning outcomes and encourage investment in major infrastructure projects such as the Western Sydney Airport.

[6] He has been critical of the direction of the Liberal Party, and has joined with his former opponent Kevin Rudd in criticising the dominance of Rupert Murdoch's News Corp in Australian political debate.

[28] Although a mediocre mathematician, Turnbull excelled in Greek, English, and History, and joined the debating and drama clubs, where he won the Lawrence Campbell Oratory Competition and starred in numerous Shakespeare plays, respectively.

[27][32] In 1987, in memory of his late father, he set up the Bruce Turnbull means-tested scholarship at Sydney Grammar, offering full remission of fees to a student unable to afford them.

[42] In 1978, Turnbull won a Rhodes Scholarship and attended Brasenose College, Oxford, where he briefly studied for a business degree before switching to a postgraduate Bachelor of Civil Law from 1978 to 1980, graduating with honours.

The Royal Commissioner's report made no adverse findings against him or Goldman Sachs,[65] however, Turnbull was one of nine defendants who settled later litigation over the collapse in undisclosed payments, thought to be worth as much as $500m.

[16] In 1982, following his retirement from politics, former prime minister William McMahon nominated Turnbull as his preferred successor in Lowe; the Liberals chose another candidate, and lost the by-election to Labor.

Turnbull's mother was close friends with Premier of New South Wales Neville Wran and Senator Lionel Murphy, who had briefly dated her in university.

As a result, the traditionally safe Liberal seat became an electoral wildcard, the contest becoming a three-person race between Turnbull, King and the Labor candidate David Patch.

[80] Announcing a cabinet reshuffle on 24 January 2006, Prime Minister John Howard promoted Turnbull from the backbench to the role of parliamentary secretary, giving him special responsibility for water at the height of the 2000s Australian drought.

[84] During the 2007 federal election campaign, Turnbull announced that if re-elected the government would contribute A$10 million to the investigation of an untried Russian technology that aims to trigger rainfall from the atmosphere, even when there are no clouds.

[89] Shortly after the vote, fellow Shadow Cabinet Minister Nick Minchin publicly suggested that Turnbull's failure to consult with party colleagues before declaring his opinion to the media on issues such as an apology to the Stolen Generations was what had cost him the leadership.

[95] In June 2009, Godwin Grech, a Treasury civil servant, privately contacted Turnbull, alleging that a car dealer with links to the Labor Party had received preferential treatment under the OzCar program, sparking the 'OzCar affair'.

[97][98] The resulting embarrassment of having repeated false allegations, as well as Turnbull's demeanour throughout the OzCar affair, was judged as the cause of a subsequent significant decline in his approval ratings in opinion polls.

[100] In response, Liberal MPs Wilson Tuckey and Dennis Jensen looked to move a leadership spill motion, intending to nominate Kevin Andrews as a challenger to Turnbull.

In 2014, Turnbull announced that the Vertigan Report, a cost–benefit analysis of providing fast broadband to regional and rural Australia through wireless and satellite services, revealed that continuing the plan would cost nearly A$5 billion and was expected to produce only A$600 million in economic benefits – a return of just 10%.

Turnbull stated if the Senate rejected the bills a third time, he would advise the governor-general, Sir Peter Cosgrove, to call a double dissolution of Parliament and a federal election for 2 July.

[134] A controversy occurred during the election campaign, when the president of the Australian National Imams Council, Sheikh Shady Alsuleiman participated in an Iftar dinner hosted by Turnbull at Kirribilli House.

[155] Prior to Turnbull becoming prime minister, the parliamentary Liberal Party voted to resolve the issue of same-sex marriage by putting the question to Australian voters via a plebiscite.

[156] Enabling legislation was rejected twice by the Senate,[157][158] and so the government decided to adopt a postal plebiscite option, which involved the Australian Bureau of Statistics conducting a nationwide survey asking voters whether they would like to see a change in the definition of marriage.

[163] Members of Turnbull's government were among those embroiled in the parliamentary eligibility crisis that arose in 2017, which disqualified several parliamentarians who held dual citizenship in accordance with subsection 44(i) of the Australian Constitution.

[168][169][170][171] The Turnbull government temporarily lost its one-seat majority in the House of Representatives after Joyce's disqualification and the resignation of Liberal Party MP John Alexander, who also held dual citizenship.

However, in December 2017 both Joyce and Alexander, having renounced their foreign citizenships, contested and won by-elections in their former seats of New England and Bennelong respectively, thereby retaining Turnbull's governing majority in the House of Representatives.

Turnbull publicly criticised the Morrison government for not taking strong enough action on climate change, arguing that they should readopt his National Energy Guarantee (NEG) policy.

In a piece in The Guardian, he stated that, "Scott Morrison can't afford to waste the bushfire crisis when Australia urgently needs its own Green New Deal...There are simply no more excuses.

In the speech, he stated that Taiwan was under a greater threat from local actors who spread lies than external forces, seemingly hinting at recent issues involving China.