Kevin Rudd was for years the darling of Australian politics before experiencing a rapid decline that saw him dumped as Labor leader in a brutal party-room coup by Julia Gillard in 2010.

Party sources say he never accepted his relegation from prime minister to foreign minister and has always wanted his old job back.

With speculation at fever-pitch this week that he now intends to make his move, Rudd sensationally resigned as the country's top diplomat in a hastily-convened midnight press conference in Washington on Wednesday.

"The simple truth is that I cannot continue to serve as foreign minister if I don't have Prime Minister Gillard's support," he said.

"I therefore believe the only honourable course of action is for me to resign."

Rudd also spoke of his sudden dumping as prime minister, saying: "We all know that what happened then was wrong and must never happen again."

His daughter Jessica immediately tweeted: "Effing proud of you, Dad xxxx". His wife Therese Rein responded: "Me too, Kevin xxxx".

Rudd, who successfully underwent heart surgery last August to replace an aortic valve, plans to head back to Australia this week and make a full statement on his future before parliament resumes on Monday.

Known for his volatile temper, 54-year-old Rudd came from humble beginnings to lead the Labor Party and oust long-time conservative leader John Howard by a landslide in 2007 to become prime minister.

The fluent Mandarin speaker promised closer engagement with Asia and wowed voters with a landmark apology to Australia's Aborigines for their treatment under white rule.

The assured, if bookish, leader unravelled Howard's harsh immigration policies and kept Australia recession-free throughout the financial crisis, something no other advanced economy achieved.

With the opposition in disarray, Rudd consistently topped opinion polls in an enduring love affair with the Australian public, until the ardour suddenly cooled in 2010 and Gillard pounced.

Rudd endured a tough childhood, forced to temporarily sleep in a car aged 11 when his family was evicted from their Queensland farm following his father's death in a road accident.

He said that experience shaped his views on social justice that led him to run for federal parliament, where he was elected in 1998 on 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.

He is married with three children and his wife Therese is a millionaire businesswoman -- facts that plays well with female voters.

In November 2007, he and Gillard together brought the Labor Party back to power in a landslide after 12 years in the political wilderness.

The start of Rudd's downfall can be traced back to December 2009 when an attempt to pass vaunted emissions trading laws ended in embarrassing failure.

An immediate drop in the polls was compounded by a botched home insulation scheme which resulted in workers' deaths and a series of house fires.

He then announced he had shelved until 2013 plans for the carbon trading scheme aimed at slowing global warming, which he had branded the "greatest moral challenge of our generation", a move that saw his public support plunge.

Rudd was further savaged in a very public dust-up with the powerful mining industry over plans for a new tax on resources profits -- a levy which ultimately led to his political demise as his poll numbers plummeted.

Despite his dumping as prime minister Rudd remains popular with voters, consistently coming out on top as preferred leader ahead of Gillard who is struggling in the polls, with elections due in 2013.