Kevin Rudd ousted Prime Minister Julia Gillard as leader of Australia's Labor Party Wednesday, by winning 57 votes to 45 in a leadership ballot of the party's lawmakers.
The change comes ahead of a general election due in September, which polls suggest Labor is set to lose, BBC reported.
The Wednesday's result was the latest twist in a long and bitter rivalry between the two politicians. But it could be the last as Gillard, the country's first woman prime minister, decided to retire from politics.
"I will not re-contest the federal electorate... at the forthcoming election," said Gillard.
"What I am absolutely confident of is it will be easier for the next woman and the woman after that and the woman after that, and I'm proud of that," she added.