Labor frontbencher Bill Shorten is set to announce his intention to stand as a candidate for the party leadership.
Mr Shorten is expected to hold a media conference in Melbourne later today to say that he wants to lead Labor in opposition, a spokeswoman from his office told AAP.
He will be the first Labor MP to formally put his hand up for the job.
But he'll have to wait until Friday's ALP caucus meeting in Canberra to be formally nominated.
Fellow former minister Anthony Albanese is thought to be another likely contender for the job.
Former trade minister Richard Marles earlier urged Mr Shorten, Mr Albanese and any other Labor MP interested in the leadership role to put up their hand by Friday's caucus meeting.
"This is a big decision for whoever decides to do it," he told Sky News.
"But I do think we need to have a sense of who's putting their hands up by the time that we meet on Friday."
He praised both Mr Albanese and Mr Shorten but declined to endorse either one as a preferred candidate.
Social media campaign for Albanese surfaces
A social media campaign is underway backing Mr Albanese as the next federal Labor leader, with supporters convinced he would defeat Mr Shorten if the choice goes to party members.
A day after being launched, the "Anthony Albanese for Labor Leader" Facebook page had attracted more than 700 "likes" on Tuesday evening.
The "albo4leader" Twitter handle meanwhile was reporting a spike in "albomentum".
The group claims it isn't connected to the outgoing deputy prime minister, and understands the Sydney-based MP hasn't yet thrown his hat in the ring.
"But it's obvious he's the best candidate to unite and lead Labor!" states a message on the Facebook page, below an image depicting a young, long-haired Mr Albanese from his university days.
One of the group's co-convenors Luke Whitington, a New South Wales Labor Policy Forum member, said Mr Albanese was a strong parliamentary performer and the best person to return the party to federal government quickly.
Mr Albanese had always proven he'd put the party before himself and had the trust of its rank and files members, he added.
"I think that if given the chance, he'd win a vote amongst the party members overwhelmingly," Mr Whitington told AAP on Tuesday.
The group is appealing for Mr Albanese to contest the top job under new rules which give grassroots members a say.
If there are two or more candidates, the leadership for the first time will be decided in a ballot weighted 50 per cent to the caucus and 50 per cent to grassroots members of the ALP.
Party heavyweight Bill Shorten appears on track to take the federal Labor leadership at a caucus meeting in Canberra on Friday.
But the unendorsed group backing Mr Albanese has demanded there be no backroom deals, warning Labor's rank and file members will be palpable if Mr Shorten were installed without a ballot.
"I think there should be more elections, there should be more democracy, members should have more of a say," Mr Whitington said.