SYDNEY (AFP) - Former union chief Bill Shorten was elected Australia's new Labor leader on Sunday, with the party pledging to draw a line under years of infighting that saw two prime ministers toppled.
Shorten, an ambitious former head of the Australian Workers' Union, beat ex-deputy prime minister Anthony Albanese in a month-long leadership race which went to a combined vote of Labor MPs and the party's rank-and-file members for the first time in its history.
Shorten, 46, secured victory by winning 55 of the 86 votes on offer from his parliamentary colleagues - some 64 percent - despite Albanese winning 60 percent of the popular membership vote.
Both ballots were weighted equally, meaning Shorten won 52.02 percent of the combined total.
"Today is a brand new day for the Australian Labor Party," a "humbled" Shorten said, promising to renew "the trust of hundreds of thousands of Australians".
"The leadership disunity of the past is just that - it's in the past."
Albanese said the party would unite behind Shorten, adding that he "will be a great Labor leader, he has my total loyalty in that position".
"Labor is stronger and more united than we have ever been before," said Albanese, warning Prime Minister Tony Abbott that the "honeymoon is over, baby".
The new leadership election process was recently introduced by former premier Kevin Rudd, who was ousted in his first term by deputy Julia Gillard and went on to topple her three years later, angering voters and prompting a Labor rout at last month's elections in favour of the Abbott-led conservatives.
Shorten acknowledged that it was a very tight result but noted that he had won a convincing majority of votes from "my parliamentary colleagues who know me best".
Interim Labor leader Chris Bowen dismissed suggestions that the closeness of the result meant leadership divisions would continue to trouble Labor or that the party membership would be disillusioned by their favoured candidate losing out.
"Yes, the branch members will be disappointed that their candidate didn't win, but I think they'll be very grateful to have had their say," he said.
He also defended Shorten against criticisms over his central role in the coups against both Rudd and Gillard, insisting the rancour was now behind Labor.
"It's true to say that we've had our issues over recent years when it's come to leadership," he said.
"We passed that today by embarking on a whole new process... opening up the decision to the entire party." National Labor president Jenny McAllister said the party now began "this twentieth chapter in federal Labor's story as a bigger, more inclusive, more democratic party".
Shorten shot to fame during the 2006 Beaconsfield mine collapse, when he became the public spokesman for two miners trapped underground for two weeks.
He entered parliament the following year.
A lawyer by training, Shorten is the son-in-law of Governor-General Quentin Bryce, Queen Elizabeth II's representative in constitutional monarchy Australia with the power to dismiss the government in cases of legislative deadlock.
Abbott said Bryce had offered her resignation after Shorten's victory to address any perceptions of a conflict of interest, but he had knocked her back due to his government's sizeable majority in the lower house and fact that her term expires in March.
"I have thanked her for her magnanimity but declined to accept her resignation, instead asking that she conclude her full term," the prime minister said.