The numbers battle for the Labor leadership has begun in earnest with the former attorney-general Robert McClelland breaking ranks to declare his support for Kevin Rudd.
Earlier this afternooon resources minister Martin Ferguson became the first cabinet minister to throw his weight behind Mr Rudd in a day where one after the other of his colleagues have lined up to trash the former foreign minister.
Mr Rudd's campaign has also been bolstered by Kim Carr - another former cabinet minister and Left faction heavyweight - and the outspoken Victorian Senator Doug Cameron.
Mr McClelland, who was demoted to emergency services minister last year in a cabinet reshuffle, told Fairfax: "I'll be supporting Kevin again on the basis that he's our best prospect to win the next federal election. Kevin is the only Labor leader to win in his own right in 17 years.
"In circumstances where the party's primary vote has been flatlining for 12 months, we have an obligation to put forward our best leader to the voters."
It comes as it was revealed that Mr Rudd sought to contact the Greens Leader, Bob Brown and key independent MPs immediately after his shock resignation in Washington DC late last night.
Mr Ferguson said he believed Mr Rudd was the best candidate to take on Opposition Leader Tony Abbott at the next federal election.
The announcement is the latest in a swinging pendulum of senior MPs to declare their support for Ms Gillard or Mr Rudd although the Prime Minister has claimed the lion's share of public caucus support to date.
Earlier today, Senator Brown revealed that Mr Rudd had tried to contact him from Washington but he could not answer the call as he was in transit.
The Greens leader said he expected the Prime Minister, Julia Gillard, to win the leadership ballot — to be held in Canberra on Monday — and criticised Mr Rudd for resigning while on foreign soil.
He believed the Greens could work with Mr Rudd as prime minister, but discounted it as a "highly unlikely scenario".
"I'm expecting Julia Gillard will be prime minister until the next election," he said.
The Greens would work with whoever Labor appointed as its leader, he said.
"If Kevin Rudd had been there (as prime minister) it would have been the same, but remember in the preceding 14 months I was not able to get in a conversation with Kevin," he said.
"I have since then."
Independent MP Tony Windsor also revealed today that Mr Rudd had phoned him following his shock resignation but said that the former prime minister had not expressly asked for his support.
Mr Windsor said he doubted there would be a change in leadership but that if there was his support could not be guaranteed in the House of Representatives.
"I've got as much chance of being prime minister as Kevin has, given the Labor caucus at the moment," he said.
"We are talking about something that is not going to happen but if it was to happen, all bets would be off . . . Maybe it's time that the people had their say in terms of who can govern."
Independent MP Rob Oakeshott said the ugly Labor leadership brawl was starting to threaten the stability of the parliament.
Mr Oakeshott - who has consistently said he would review his support for the minority government if Labor changed leaders - said he was keeping a close eye on the situation.
Senior Rudd-supporter Kim Carr has publicly lashed out at his colleagues, declaring he won't be intimidated by a campaign of vilification and he won't be in the business of making advertisements for the Liberal Party.
Senator Carr, from the Victorian Labor left, strenuously denied that Ms Gillard's 2010 election campaign had been derailed by a campaign of destabilisation run by Mr Rudd. ''The 2010 campaign was characterised by many examples of miscalculations and poor judgments,'' Mr Carr said.
Senator Carr, who was demoted by Ms Gillard in a recent reshuffle, urged Labor's National Executive to release the full version of a review of the campaign ''not just the leaked version''.
''I'm not going to be intimidated by this campaign of vilification,'' Senator Carr said. ''We need decent rules of engagement because we all have to live together with each other after this event. I won't be in the business of making ads for the Liberal Party.''
His comments come as a growing number of senior ministers speak out publicly against Mr Rudd, including Simon Crean, Wayne Swan, Craig Emerson, Tanya Plibersek, Nicola Roxon and Stephen Conroy.
Immigration Minister Chris Bowen — who is considered a Rudd supporter — urged his former leader to run in the leadership ballot.
Mr Bowen said that Mr Rudd deserved respect as a former prime minister and leader of the party.
But Mr Bowen stopped short of declaring his allegiance either way saying the Labor Party had a "serious" choice to make between two "very good" candidates.
"I think we need to have a mature, sensible discussion," he said.
Mr Bowen denied that he had been offered either the Treasurer's position or the deputy leadership — as previously reported — under a rebooted Rudd leadership.
This afternoon, Families Minister Jenny Macklin declared her unequivocal support for the Prime Minister.
"My support on Monday will be very strong with the Prime Minister," she said.
Defence Minister Stephen Smith said he would back Ms Gillard as Mr Rudd had, in the final days of his prime ministership, become "impossible to work with".
- with Josh Gordon