Australia's prime minister Julia Gillard has put her job on the line, announcing a leadership ballot in hopes of quashing a comeback by the premier she ousted in a Labour Party coup.

But Kevin Rudd's supporters said that even if Ms Gillard survives Monday's vote, the turmoil surrounding her unpopular government will continue until she is out.

Mr Rudd, who resigned as foreign minister during an official visit to the US, told reporters in Washington that he thinks Labour will lose next year's elections if Ms Gillard remains leader, and that government colleagues are encouraging him to run.

But he would not say whether he would challenge Ms Gillard in the leadership ballot of Labour politicians until he returns to Australia.

Ms Gillard said she will abandon her leadership ambitions if Labour politicians choose Mr Rudd over her on Monday, and called on Mr Rudd to do the same if he loses. "We need a leadership ballot to settle this question once and for all," she told reporters.

But Rudd supporters said he would continue to destabilise the government if he lost the ballot and would try to win another ballot at a later date. A Rudd supporter, Senator Doug Cameron, said a Monday poll would be unfair because Mr Rudd would not have time to canvass support. "It's clear that some senior ministers are intent on putting a stake through Kevin Rudd's heart and I don't think that's justified," Mr Cameron told Australian Broadcasting Corp television.

Ms Gillard ousted Mr Rudd as prime minister in June 2010 in an internal coup, and their centre-left Labour Party scraped through elections later that year to lead a minority government.

Polls now suggest Labour would suffer a devastating defeat, but Ms Gillard maintains she has her colleagues' support.

Many Australians were angry when the government dumped Mr Rudd, who was swept into office as prime minister by general elections in 2007. In Australia's system, the prime minister is chosen by a majority of politicians in the House of Representatives, not by voters.

Labour politicians moved against Mr Rudd in 2010 because opinion polls suggested they were unlikely to win elections that year under his leadership. After the 2010 elections, Labour under Ms Gillard formed the first minority government in Australia since the Second World War.