Prime Minister Julia Gillard is staying defiant in the face of pressure on her leadership, insisting the issue was settled in March.
Asked whether she was confident about the support of Labor's caucus, Ms Gillard said on Monday morning: "Absolutely."
But the Prime Minister's comments were contradicted by senior minister Greg Combet, who said Labor must settle its leadership crisis this week, saying the "ball's in Kevin Rudd's court".
"We certainly can't have this go on," Mr Combet told ABC radio on Monday morning.
"It's just got to be resolved."
Mr Combet reiterated his support for Ms Gillard, saying she would not be stepping aside and nor would any senior cabinet ministers be "tapping her on the shoulder to go".
The leadership speculation could not continue until the election, he said.
"Kevin Rudd has to decide whether he's a candidate or not and then do something about it," Mr Combet said.
"The Prime Minister is not going to step down so the ball's in Kevin Rudd's court."
Labor MP Darren Cheeseman, a Rudd supporter who occupies the ultra-marginal Victorian seat of Corangamite, has lashed out at cabinet ministers who have attacked Mr Rudd through the media.
"Three years on, and again we have senior ministers attacking Kevin Rudd, some of us are still fighting to win our seats," Mr Cheeseman wrote on Twitter.
Last week Mr Cheeseman played down the prospect of a leadership change.
"We will be proceeding to the election with Julia as our leader," he told reporters as he left Parliament House on Thursday evening.
As Ms Gillard starts what is shaping up to be her toughest week in Parliament, a review of opinion polls indicates that Mr Rudd's three-stage siege on the Labor leadership has cost the party direct political support and could destroy it for a generation.
The review by Gillard supporters is of opinion polls before and after Mr Rudd's two previous leadership tilts.
Its release represents a new stage in the internecine warfare between the current and former prime ministers as Labor MPs stare electoral annihilation in the face.
A senior minister has told Fairfax Media that the only certain effect of Mr Rudd's "revenge mission" has been to send the ALP's stocks into the basement, guaranteeing that Tony Abbott will be prime minister after the election.
The figures, based on the results of the monthly Fairfax-Nielsen poll, the fortnightly Newspoll, and others, show Labor's standing with voters has headed south immediately following the last two raids on the top job by Mr Rudd and his backers.
The most recent Fairfax-Nielsen and Newspolls show Labor's primary vote at 29 per cent and the gap widening between Ms Gillard and Mr Abbott in the preferred prime minister category.
Newspoll on Monday has Mr Abbott as leading Ms Gillard by 12 percentage points as preferred prime minister, 45 to 33 per cent.
Meanwhile, the Australian Services Union's NSW secretary, Sally McManus, has confirmed that she sent an email to members asking their opinions on the Labor leadership.
"I'm not doing that in order to get any publicity about it," Ms McManus said in a voicemail message to Fairfax Media.
"At the moment it's between me and my members . . . Probably I'll leave the poll open for a couple of days and after that be in a position to talk to people."
Support from the unions is critical to Ms Gillard's hold on power. Australian Workers' Union boss Paul Howes in particular has backed the Prime Minister's continuing leadership.
Other Labor MPs arriving in Canberra on Monday morning for the final sitting week of Parliament vented their frustration at the crisis engulfing their party.
Western Sydney MP Laurie Ferguson, who supports the Prime Minister, said the Labor Party had been through three years of division because of Mr Rudd's "self-interest".
"It's about time it stopped," Mr Ferguson said.
"It's been resolved three times, he's defeated, he's challenging, he doesn't challenge. Like for Christ's sake."
Labor backbencher Graham Perrett also expressed frustration saying: "I'm not a general, I'm just a backbencher doing my bit to win my seat.
"I don't give a rat's about polling. I do my job irrespective whether the polls are up or down."
Many MPs within the Labor Party are now agitating for a caucus ballot this week to resolve the leadership conflict.
One MP told Fairfax Media he thought the ballot would be held on Thursday and that the party was heading for disaster if it did not go to a leadership vote.
Labor MP Stephen Jones, who supports Mr Rudd, told Sky News he agreed with Mr Combet that the leadership needed to be resolved this week.
The only way to break the deadlock was a vote in caucus, Mr Jones said. He added that it did not help having "senior cabinet members out in public talking about this issue and having shots".
"There is no doubt that Kevin Rudd is a very strong campaigner," Mr Jones said.
"And there is no doubt that if the polls are right we face a thumping loss at the September election."
with Mark Kenny
- Sydney Morning Herald