Kevin Rudd, a charismatic but hot-tempered politician with a sense of the popular mood, has capped an extraordinary political comeback by making a bid for his second election victory.

Rudd, 55, announced Sunday that a general election would be held on September 7 -- giving him a chance to keep his centre-left Labor Party in power three years after it ousted him.

It was only in late June that the Mandarin-speaking ex-diplomat was sworn in as prime minister for a second time, after he ousted his former deputy Julia Gillard in a 57-45 vote of Labor lawmakers.

Opinion polls had suggested Labor under Gillard would be doomed to defeat in the next election.

"In 2007 the Australian people elected me to be their prime minister. That is a task that I resume today with humility, with honour and with an important sense of energy and purpose," Rudd said after his party victory.

In a bid to reunite the fractious Labor camp, since taking office Rudd has abandoned an unpopular carbon tax which Gillard had doggedly stuck to.

He has also announced a radical new plan to send boat-borne asylum-seekers to Papua New Guinea and Nauru, and deny them the right to settle in Australia even if they gain refugee status.

He has also championed reforms to the Labor Party to make it harder to remove a leader.

Rudd stormed to power in 2007 with a landslide victory that ended a decade of conservative rule, campaigning for generational change with an emphasis on issues such as global warming.

He was for years a darling of the public, but his confidence with voters translated into egotism -- even megalomania -- behind the scenes, according to Labor colleagues who had, by mid-2010, lost faith in the prime minister.

A series of policy mis-steps gave party members the pretext to swoop, deposing him in a shock coup which delivered Gillard to power as Australia's first female leader. She kept him in the cabinet as foreign minister, but they made uneasy partners.

His volatile temper was on show in a video that emerged in 2012, filmed when he was still premier, showing Rudd swearing and gesticulating in frustration while trying to record a public message. He accused the Gillard camp of leaking the footage.

Rudd came from humble beginnings to head the Labor Party and oust long-serving conservative leader John Howard.

As prime minister, he promised closer engagement with Asia, made a landmark apology to Australia's Aborigines for their treatment under white rule, and ratified the Kyoto Protocol on climate change.

The assured, if bookish, leader kept Australia recession-free throughout the global financial crisis, something no other advanced economy achieved.

Rudd endured a tough childhood, forced to sleep temporarily in a car aged 11 when his family was evicted from their Queensland farm following his father's death in a road accident. He has said that experience shaped the views on social justice that led him to run for federal parliament, where he was elected in 1998 at his second attempt.

Before arriving in Canberra he was a senior bureaucrat for the state Labor government in Queensland and had a lengthy career as a diplomat, including postings to Stockholm and Beijing.

The start of his first premiership's downfall can be traced to December 2009 when he failed to pass much-vaunted emissions trading laws and badly damaged his credibility with voters.

Rudd was further savaged in a very public dust-up with the powerful mining industry over plans for a new tax on resources profits which finally sparked his ousting.

Despite his dumping as prime minister, Rudd consistently came out in opinion polls as the preferred leader ahead of Gillard.

He was finally successful in resuming his old job in his third tilt since being dispatched in 2010 -- he famously quit as foreign minister in February 2012 while in Washington to challenge Gillard, losing 31 votes to 71.

His backers agitated again for a ballot in March, but Rudd refused to stand when Gillard called his bluff and announced a sudden vote.

Rudd is married with three children. His wife Therese Rein is a millionaire businesswoman.