Kevin Rudd's backers plan to present the former prime minister with a list of supporters, with a view to convincing him to challenge Julia Gillard before Parliament rises tomorrow, the last sitting before the election.
Senior sources close to Mr Rudd told The West Australian they were "confident" that Mr Rudd had majority support in the 102-strong Labor caucus.
But their task will be to assure Mr Rudd he doesn't necessarily need the "significant majority" he has said would be a prerequisite for his return.
"There's a reason for that," Mr Rudd said in March after being a no-show in the last leadership spill, "and that is, our party needs to be united, there is no point in inheriting a disunited party."
It is understood that ALP senators Kim Carr (Victoria) and Mark Furner (Queens- land) and Victorian MP Alan Griffin began sounding out colleagues last night - using a "the king is back" pitch - with a view to collecting the names of at least 55 MPs wanting a Rudd return.
Team Rudd was co-ordinating its efforts from former immigration minister Chris Bowen's office.
Adding urgency to the Rudd camp's manoeuvring is that Mr Rudd is scheduled to fly to China tomorrow afternoon to speak at a global summit alongside former US secretary of state Henry Kissinger.
Although Mr Rudd's lieutenants said this long-scheduled visit would be ditched in the event of a leadership showdown, they are considering pursuing a petition of one-third of Labor MPs and senators to demand a special caucus meeting for tomorrow to allow a spill of leadership positions.
This has never been done before in Labor history and even though a petition of 34 signatures would guarantee a special caucus meeting is held, it would not necessarily lead to a leadership vote.
That is because the spill motion would have to be voted on separately and be supported by a majority in the room - and the PM's camp would demand a show of hands so that the disloyal were forced to identify themselves.
Gillard loyalists insist the Prime Minister will not step aside and figure that Mr Rudd does not have the courage to challenge. "He'd rather be the perpetual sook," one Labor MP said.
Labor backbencher Graham Perrett, a Gillard backer, challenged the Prime Minister's detractors to call a ballot.
Ms Gillard's address to the last scheduled caucus meeting of the 43rd Parliament yesterday was described as defiant rather than enthusiastic.