Anthony Albanese is hoping to ride a wave of popular support among Labor's 30,000 rank and file members to claim the party's leadership as it conducts an historic open ballot.
His formal tilt at the ALP's top job came at Labor's first caucus meeting since its election defeat last weekend, triggering a face-off against the right faction's rising star, Bill Shorten, 46.
The 50-year-old political ''street-fighter'' known as ''Albo'' declared he was the best person to lead his shattered parliamentary party and that he can win the next election.
The contest will see a traditional caucus ballot and a separate postal vote among the party's financial members. The process will be a month-long experiment as the party bares its internal workings under democratisation rules introduced by former leader Kevin Rudd.
Both candidates have committed to running positive campaigns, with Mr Albanese kicking off his leadership bid with high praise for his opponent.
''Bill is a friend of mine and he would make a very good leader. He's a great communicator. He is someone who I think played a critical role in the creation of Disability Care Australia in its formative stages. So he's someone I look forward to working with into the future.''
Known for his combative parliamentary style, Mr Albanese's nomination ended a week-long guessing game.
''What you see is what you get. I'm someone who puts forward a view, strongly and passionately, when I believe it. I'm someone who is prepared to argue the case, whether in the Parliament, in the media, or out there in the community,'' he said.
In a sign of just how public the process will be, Mr Shorten also held a media conference to declare that he was a builder.
''I have the energy and the enthusiasm,'' he said in comments seen by some as a subtle dig at Mr Albanese who took days to weigh his candidacy amid speculation he was tired from years of running the parliament as Leader of the House.
Former treasurer Chris Bowen has been appointed acting leader and all ministers will take responsibility as shadow ministers for their respective portfolios.
Both prospective leaders are now expected to travel the length and breadth of the land visiting ALP branches.
It is expected there will be debates between the contestants in a replication of US-style primaries, however it is not known if these will be open to the public or media.
While numbers are difficult to calculate, insiders lean towards Mr Shorten having a slight edge in the blind caucus ballot, to be conducted in the final week of the process, but say Mr Albanese is likely to be the popular favourite across the party's membership.
They point to recent membership ballots for the party presidency which favoured left-faction candidates such as Mr Albanese.
The new internal machinery for selecting Labor's parliamentary leader means the Opposition will be without a permanent leader for at least its first month.
It comes as prime minister-elect Tony Abbott finalises his ministerial line-up, which is expected to be unveiled on Monday and sworn in by midweek.
Labor's leadership process will not provide Mr Abbott an easier path in the parliament however, with both contenders vowing to block moves to scrap the carbon price, the mining tax, and other measures.
''My position is very clear - I believe in action on climate change. I helped write the policy that saw us have and support an emissions trading scheme … I could not look my son in the eye and say, 'Sorry for reasons of whatever we gave up the argument'. Climate change is real.''
A surprisingly grim-faced Mr Abbott addressed his party room for the first time in Canberra on Friday, inviting jubilant MPs to ''savour'' the victory but then get down to work.