23 February 2012
Last updated at 22:54 ET
Kevin Rudd will stand against Prime Minister Julia Gillard in Monday’s Labor Party leadership ballot.
He wanted to work to ”restore the trust” of the Australian people that she had lost, he said in Brisbane on Friday.
Ms Gillard, who ousted him as PM in June 2010, called the vote following weeks of speculation that he would challenge her for the top job.
Mr Rudd resigned as foreign minister in Washington DC late on Tuesday night.