Prime Minister Julia Gillard threw her job open to a leadership ballot Thursday as grumblings increased within government ranks over disastrous opinion polls six months before a national election.
"I have determined that there will be a ballot for the leadership and deputy leadership of the Labor Party" in the afternoon, she told Parliament.
Her predecessor Kevin Rudd, whom Gillard ousted in an internal party coup in 2010, is her most likely challenger.
The ballot for her job and that of Deputy Prime Minister and Treasurer Wayne Swan comes on the last day of Parliament before a seven-week break.
The new leadership team will be decided by 101 lawmakers within the center-left Labor Party. Foreign Minister Bob Carr is overseas and will miss the vote.
A change in party leadership could force out the minority government and hasten the national election now set for Sept. 14.
Senior minister Simon Crean brought leadership unrest to a head earlier Thursday by calling on his government colleagues to sign a petition to force a ballot if Gillard refused to call one. Such a petition would have needed the signatures of one-third of government lawmakers.
Crean — a former Labor leader who is now Minister for the Arts, Regional Australia, Regional Development and Local Government — said he wanted to be deputy leader and called on Rudd to challenge for the top post.
Part of Rudd's appeal is opinion polling that shows Rudd would be a far more popular choice of the public. Rudd's office said he would issue a statement later.
Rudd led Labor to victory at elections in 2007 before being deposed. He challenged Gillard last year and was roundly defeated in a ballot of Labor lawmakers, but recent reports have cited sources in saying he's now believed to have stronger support.
"Kevin Rudd in my view has no alternative but to stand for the leadership," Crean told reporters.
"He can't continue to play the game that says he's reluctant or he has to be drafted," he said.
"This is an issue that has to be resolved. There's too much at stake," Crean added.
Rudd lost the last leadership ballot by 71 votes to 31. The Daily Telegraph newspaper reported Thursday that Rudd now had the support of 47 colleagues, Gillard 42 and the remainder of the 102 government colleagues undecided.
A change of leader could also bring down Labor's fragile minority government, with a key independent lawmaker upon whom Labor relies to command a majority in the House of Representatives warning that his support under Rudd was not guaranteed.