Former prime minister Julia Gillard has hit out at a new rule about how the Labor Party can remove a leader, describing it as "a clumsy attempt" for bad leaders to hold onto power.
Under reforms introduced by Kevin Rudd, the only way to remove the leader is for 60 per cent of Caucus members to sign a petition requesting a new election.
The new rules also govern how the leader is selected, with a ballot of both the parliamentary Labor Party and rank-and-file members taking place.
The first contest governed by these rules is underway, with Bill Shorten and Anthony Albanese beginning a month-long campaign to win the job of opposition leader.
The ABC understands Ms Gillard supports the decision to give party members a say, but does not agree with the rules surrounding the removal of a leader.
Ms Gillard has used an essay in The Guardian to say that represents "exactly the wrong approach", protecting poorly performing incumbents instead of the best candidate.
"These rules literally mean that a person could hang on as Labor leader and as prime minister even if every member of cabinet, the body that should be the most powerful and collegiate in the country, has decided that person was no longer capable of functioning as prime minister," she writes.
"A person could hang on even if well over half of their parliamentary colleagues thought the same.
"Ironically, I argue against these rules, even though under them I would have unseated Kevin Rudd in 2010, given colleagues would have signed up in sufficient numbers to have him gone, but he could never have defeated me in 2013."
Anthony Albanese and Bill Shorten (pictured) will both stand for the Labor Party leadership. Political correspondent Simon Cullen explains how the new voting rules work.
Ms Gillard says Labor should move on from determining its leader "on the basis of opinion polls, or the number of positive media profiles, or the amount of time spent schmoozing media owners and editors, or the frippery of selfies and content-less social media."
She also says the party needs to "think deeply" on cultural factors that allow leaking and destabilising to be "so richly rewarded".
Despite her criticism of the rules, Ms Gillard describes Mr Shorten and Mr Albanese as "two worthy candidates".
"I hope whoever is the victor in the current leadership contest serves as Labor leader for a long time, and the next time Labor needs to choose a new leader is after the next period of Labor government," she said.
"Achieving that requires much more than a ballot. It requires a true acceptance by all of the result of the ballot. Solidarity, not destabilisation. This is where Labor has failed."
Ms Gillard said Labor had a strong record to be proud of, pointing to the disability insurance scheme, workplace relations, education reform and carbon pricing.
"Labor should not in opposition abandon our carbon pricing scheme," she said.
"Climate change is real. Carbon should be priced. Community concern about carbon pricing did abate after its introduction.
"Tony Abbott does not have a viable alternative."
Ms Gillard also admitted she had "erred by not contesting the label 'tax' for the fixed price period of the emissions trading scheme I introduced".
"I made the wrong choice and, politically, it hurt me terribly," she said.
Burke 'surprised' by enthusiasm over member ballot
Ms Gillard's comments on the leadership rules echo those made by Labor Senator Stephen Conroy during the week.
He said the rules make Labor look like a "laughing stock" while allowing the Coalition to "get away with murder".
Senior Labor MP Tony Burke admits he was cynical about the new rules but says his view has changed over the last couple of days.
"I have been genuinely surprised by the enthusiasm that's there among branch members, by the excitement that I'm having from people in the street, saying that they're actually interested in joining the Labor Party and from the participation that might come from this," he told ABC News 24.
"In a month's time we will have gone through the process and we'll be able to judge whether it worked, whether it didn't, what they actually thought of it.
"But I must say, a lot of the objections that I've always had, as to whether or not this would be practical - for the first couple of days watching it in operation, I've been wrong."
He says it is likely the party will reassess the 75 per cent threshold for the Caucus to remove a leader.
"Everything will get looked at later. The 75 per cent principle was set very, very high and I imagine that one will be looked at," he said.
Shorten, Albanese vow to run positive campaign
Mr Shorten and Mr Albanese announced this week they would stand as candidates, and have vowed to run a civil and positive campaign.
They will now travel around the country meeting the up to 40,000 rank-and-file members who now have a say in the party's choice of leader - although exactly who is eligible to vote is still being worked out.
Party members will have their ballot first, followed by the Caucus. Both ballots will have an equal weighting.
Newly-elected Labor senator Sam Dastyari says Mr Albanese would be a fantastic leader but he thinks Mr Shorten is the better candidate.
"He'll be able to articulate a strong case for the future of the Labor Party and I think he's a greater break from the past than Anthony is," Mr Dastyari said.
"But look, this has got really exciting. It's really exciting that tens of thousands of Labor Party members across the country are going to have a say in a ballot process."
Party officials will meet on Monday to discuss exactly who will be eligible to vote, and Mr Dastyari has indicated he wants the ballot to be as broad as possible.
"The more people involved in deciding the Labor Party leader, the better," he said.
Mr Shorten is favoured to get Caucus support but Victorian Labor MP Kelvin Thomson acknowledges it is possible the next leader might not have a majority backing.
"It's inherent in the system that if you're going to give party members a say, they may exercise that say," he said.
"This is an experiment. It's the first time we've done it.
"If the party membership prefers a particular leader, well, so be it."
Social media campaign favours Albanese
Luke Whitington, founder of the social media campaign Albo for Leader, says Mr Albanese has the overwhelmingly support of party members.
"His personal story is very compelling," he said.
"Every step of the way - from being a housing commission boy of a single mum, through his education, up to being deputy prime minister - every challenge, he has met and exceeded expectations.
"I think people can recognise that. They know he is a genuine guy."
Mr Whitington says he wants to see debates between the candidates.
"I think that'd excite people, get people involved," he said.