A second Australian government minister has quit in the fallout from a bungled leadership ballot.
The failed attempt to depose Prime Minister Julia Gillard reinforced perceptions of a crisis in her administration six months before national elections.
"This is the honourable thing to do," Chris Bowen said after Ms Gillard accepted his resignation as minister of tertiary education, skills, science and research.
She had already dumped the senior minister who forced her to call the leadership ballot before her expected challenger refused to run. A junior minister and three officials within the centre-left Labour Party have departed as well.
Australian prime ministers are chosen by politicians within the ruling party, and a leadership change is often considered as a solution to abysmal opinion polling.
Former prime minister Kevin Rudd stunned many with the 11th-hour announcement that he would not challenge her. His office said that "there are no circumstances under which he will return to the Labour Party leadership in the future". He explained that he was keeping a vow made when he lost a leadership ballot to Ms Gillard a year ago that he would not challenge again.
Ms Gillard said she was surprised that Mr Rudd had not taken a shot at the top job. Part of his appeal is that opinions polls show he is far more popular with voters than Ms Gillard.
Senior minister Simon Crean, who brought the leadership crisis to a head by calling on his government colleagues to force a ballot, was sacked, and junior minister Richard Marles, a rising star who publicly backed Mr Rudd, resigned late on Thursday. Another three Rudd supporters have resigned from senior positions within the party organisation - Joel Fitzgibbon, Ed Husic and Janelle Saffin.
None has quit politics so the government's slender parliamentary majority with the support of independents remains unchanged.
The government ranks are split over whether by avoiding a showdown with Ms Gillard, Mr Rudd had let down his supporters who have worked behind the scenes to undermine her leadership in the face of their likely defeat at national elections on September 14.