Support for Kevin Rudd among Labor MPs appears to have grown, placing the former prime minister potentially within striking distance of Prime Minister Julia Gillard in the event of another challenge.
Estimates put his backing as high as 45 votes out of 102 Caucus members, although Ms Gillard's supporters insist it is lower.
The shift in sentiment follows Labor's trouble-plagued start to the election year, which has shaken MPs and fuelled perceptions of disorder.
Adding to Ms Gillard's discomfort, two of her most senior ministers on Monday said Mr Rudd was an electoral asset.
''I think he is an asset and we should use him, but it has to be a disciplined asset,'' said Arts and Regional Development Minister Simon Crean.
Mr Crean was one of Mr Rudd's harshest critics last year but believes the party would benefit from his popularity.
Ms Gillard's chief parliamentary tactician, Transport Minister Anthony Albanese, also called for Mr Rudd to be returned to the fold.
''Kevin Rudd is an asset to the Australian Labor Party,'' he told Sky News. ''We need to engage Kevin Rudd and use him wherever possible. He's a very popular figure, there's no doubt about that.''
With her leadership now facing greater scrutiny, Ms Gillard on Monday pleaded for loyalty.
At the first ALP caucus meeting for the year, she blamed internal disloyalty for some of Labor's problems, revealing that journalists had told her that MPs had been waiting for the return from holidays to complain about her leadership.
One caucus member, however, said Ms Gillard ''needed to look closer to home''. The MP said Ms Gillard had enjoyed the backing of most MPs during 2012, but this support had noticeably weakened on the back of ''a terrible start'' to the election year.
''We needed to make every post a winner in order to catch the Coalition by polling day, but it hasn't gone to script so far, not at all,'' the MP said.
A series of self-inflicted political wounds has sapped morale and reignited talk about whether anything would be achieved by another leadership change.
These blows include the clumsily handled dumping of Northern Territory senator Trish Crossin and the timing of the election announcement, which was followed closely by the resignations of two senior ministers.
Ms Gillard's reduced support, confirmed to Fairfax Media by multiple sources from both sides of the
caucus, raises the possibility of a second leadership challenge by Mr Rudd, although his supporters say no move is imminent.
Estimates put Mr Rudd's numbers as high as 45 votes - a figure regarded as ''not unrealistic'' by a key Gillard backer, who put it ''closer to 40''.
While Mr Rudd would need 52 votes to win, it is thought that backing in the mid-40s would be enough to build momentum in a leadership ballot.
He received just 31 votes to Ms Gillard's 71 in the bruising leadership ballot a year ago. In the immediate aftermath of that challenge, Ms Gillard's backers believed her two-to-one margin would be sufficient to end the Rudd threat.
However, the former foreign minister has not only remained in politics but has recently begun to ramp up his public profile.
Last week he returned to the the Seven Network's Sunrise program, appearing with the opposition's Joe Hockey. That pairing reprised his regular appearances on the high-rating show that helped to make him a household name in 2006 - a key factor in his rise to the Labor leadership that year.
Voter support for the government, which had been slowly recovering throughout the second half of 2012, has tanked again, according to two separate polls published in News Limited papers.
Labor MPs are particularly concerned about the decline in Ms Gillard's personal standing compared with that of Opposition Leader Tony Abbott.
According to Newspoll, Ms Gillard's standing as preferred prime minister has deteriorated by 4 points to 41 per cent, while Mr Abbott's has climbed by 6 points to 39 per cent in the two weeks since the previous poll.
The poll also showed that the number of people satisfied with her performance has dropped, while the number of those dissatisfied has risen. The opposite was the case for Mr Abbott. The Opposition Leader used a pep talk to his frontbench yesterday to presage a more positive approach to combat Labor's branding of him as ''Dr No''.
''People expected us … to hold the government to account, and we certainly did that, but I think what people are now looking for is for a little bit more from us,'' he told them.
''They want us not so much to be an opposition but to be an alternative government … and that is exactly what you've been getting over the last few weeks.''
With Labor bracing itself for another tough parliamentary session from Tuesday, Mr Crean said the party could win in September despite the recent setbacks.
''We are behind and I have acknowledged that. But we can win. It is difficult but we have to hold our nerve and our conviction and our belief, not just in what we've done but what we plan to do.''