Julia Gillard is set to win Labor's leadership ballot, but challenger Kevin Rudd has voiced MPs' fears it won't be the end of the instability dogging the minority government.
The prime minister has urged the 102 caucus members attending the challenge in Canberra's Parliament House at 10am (local time) on Monday to end the "destabilisation" campaign run by Mr Rudd and his backers.
The Rudd side is claiming between 30 and 35 votes, while the Gillard camp is claiming just under 70 votes, with four votes undeclared and one absentee.
In her election-eve pitch, the Ms Gillard said on Sunday said she was feeling "determined" and believed caucus would unite after the ballot to bury the leadership issue once and for all.
"At the end of what has been a very difficult week, the things that unite us in the Labor Party are far, far stronger than anything else," she told reporters in her Melbourne electorate of Lalor.
"We will unite tomorrow and we will get our shoulders to the wheel delivering Labor's programs and plans."
However, Mr Rudd feared speculation about the Labor leadership could remain despite him promising to go to the backbench and not challenge Ms Gillard a second time before the next election.
"There is a fear, on the part of many, that other folk will line up and have a go at whoever the leader is who emerges from Monday - now be it myself or Julia - and I would be very concerned if that were to happen," Mr Rudd said.
The man who was deposed by Ms Gillard in June 2010 also called for unity after the ballot.
"If Julia is returned on Monday then she will have my unequivocal support between now and the next election because we have interests way beyond individuals here," he told the Nine Network on Sunday.
"It's time for us to unite rather than divide."
The calls for unity on Sunday came after Rudd supporter Anthony Albanese made a heartfelt speech on Saturday in which he declared his love for the party and despaired that Labor's legacy of good government since 2007 had been devalued by the infighting.
Asked why anyone should believe he wouldn't have another tilt at the leadership in this term, Mr Rudd said he would adhere to what he had promised.
"If Julia is returned, or if I'm elected, then I think it's time for various of the faceless men (of the Labor factions) to lay down the cudgels," he said.
Mr Rudd's most senior supporter, Resources Minister Martin Ferguson, said a number of Labor figures had made "disgraceful" comments over the past week and Monday's vote must end the internal hostilities.
"Kevin Rudd won't come again," he said.
Ms Gillard rejected the Rudd backers' central claim that his greater popularity - borne out consistently in opinion polls - would give Labor a better chance of winning the 2013 federal election.
"You don't look at the opinion polls to work out what you believe in and what the nation needs," she said.
"You look inside yourself, to your core beliefs, to your core Labor beliefs and then you go and get it done," she said.
Opposition Leader Tony Abbott, who needs four extra votes in the House of Representatives to bring down the government, repeated his calls for an early election and appealed to independent MPs to support a no-confidence motion in parliament.
"I say to the independent members of parliament, you gave us this mess, you fix it," Mr Abbott said.
"You are responsible for this government."
A senior coalition figure said it was "highly unlikely" a no-confidence motion would be moved this week unless the independents made public statements in support of one.
The coalition launched a new ad in its Kevin O'Lemon series on Saturday night, attacking Labor over its disunity and adding a new "lemon" character - potential future challenger Bill Shorten.
Three ministers - Peter Garrett, Nicola Roxon and Tony Burke - have said they would not serve in a Rudd cabinet.
Treasurer Wayne Swan, who last week made a scathing attack on Mr Rudd's leadership style, declined to say what he would do as he expected Ms Gillard would be returned.
Mr Swan also said he believed Mr Rudd's promise he would not challenge a second time.