TEMPO.CO, Canberra - Australia's prime minister-designate Malcolm Turnbull on Tuesday assured the country that his government remained strong despite an internal party revolt that made him the nation's fourth leader in little more than two years and will leave deep divisions in his administration's ranks.

Turnbull will be sworn in as Australia's 29th prime minister on Tuesday after a surprise ballot of his conservative Liberal Party colleagues voted 54-to-44 on Monday night to replace Prime Minister Tony Abbott only two years after he was elected. Turnbull's elevation has cemented a culture of disposable leaders as the new norm in Australian politics since the 11-year reign of the Prime Minister John Howard ended in 2007.

"There's been a change of prime minister, but we are a very, very strong government, a very strong country with a great potential and we will realize that potential working very hard together," Turnbull told reporters as he left his Canberra apartment on Tuesday morning.

"This is a turn of events I did not expect, I have to tell you, but it's one that I'm privileged to undertake and one that I'm certainly up to," he added.

Turnbull, a 60-year-old former journalist, lawyer and merchant banker known for his moderate views, was party leader for two years before he was ousted in 2009 by Abbott by a single vote in a similar leadership ballot.

Abbott, a 57-year-old former Roman Catholic seminarian, has been described as the most socially conservative Australian prime minister in decades, while Turnbull is considered not conservative enough by the right wing of the party.

Turnbull's return to the helm will likely lead to a major cabinet reshuffle, with Treasurer Joe Hockey and Defense Minister Kevin Andrews among the ministers who publicly supported Abbott.

Andrews, a senior figure in the party's right wing, on Tuesday argued that he should retain his defense portfolio.

Andrews challenged Foreign Minister Julie Bishop, a Turnbull supporter, for the Liberal Party's deputy leadership on Monday night, but was defeated by a vote of 70 to 30.

"I did it as a way of reaching out and saying to him that I can work with him, that I believe other people like me can work with him, and that's what we've got to do," Andrews told the Australian Broadcasting Corp in explaining his challenge to Bishop. "There's always hurt and frustration and grief at these circumstances. That's natural. That's human."

Abbott has yet to make public whether he intends to quit or stay on in politics.

Unlike Abbott, Turnbull has supported Australia making polluters pay for their carbon gas emissions to reduce the nation's greenhouse gas emissions and legalizing gay marriage.

But Bishop said the government's policies would not change without consultation with Liberal Party lawmakers.

"The policies remain until they're changed and they're only changed through a process of discussion and consultation with the party room," she said.

She said the party had moved against Abbott because he had not made good on a promise made in February to improve the government's standing in opinion polls within six months.

"He asked for six months to turn things around. Well, seven months later a majority of the party room felt he hadn't done that," Bishop said.

The political turbulence comes as Australia enters its record 25th year of continuous economic growth. However a cooling mining boom that helped Australia avoid recession during the global financial crisis has slashed tax revenue and slowed growth while a hostile Senate has blocked key parts of the government's financial agenda.

The Liberals were elected in 2013 as a stable alternative to the then-Labor government. Labor came to power under Kevin Rudd at elections in 2007, only to dump him for his deputy Julia Gillard in 2010 months ahead of elections. The bitterly divided and chaotic government then dumped Gillard for Rudd just months before the 2013 election.

Successive opinion polls showed that the government was likely to lose at elections in September next year under Abbott's leadership.

Opinion polls show that Turnbull is more popular than Abbott, but many of those who prefer him vote for the center-left Labor Party.

AP