Foreign Minister Bob Carr has suggested Labor could be heading for a heavy defeat in the federal election, warning voters the coalition could damage Australia "with a big majority".
The latest opinion poll puts the coalition on track to win 54 per cent of the two-party vote with the ALP on 46 per cent.
Senator Carr is in St Petersburg representing Australia at the G20 Leaders' Summit.
"I remain optimistic and I just urge people to think what a conservative government with a big majority would be tempted to do," Senator Carr told AAP on Friday.
The foreign minister's warning that a Tony Abbott-led government could have a large parliamentary advantage is in stark contrast to his comments just 24 hours earlier.
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On the first day of the St Petersburg summit, Senator Carr told reporters: "I'm only contemplating a Labor win."
"Yes, against the suggestions in the polls, but a Labor win based on the fact that people will vote for jobs and their economic security not for the cuts that Tony Abbott is promising," he said on Thursday.
Senator Carr is filling in for Prime Minister Kevin Rudd at the G20, which has so far failed to close deep divisions among world leaders on how best to handle the crisis in Syria.
Campaigning in NSW on Friday Mr Rudd insisted Labor was still in with a chance of winning.
"There is fight in the old dog yet," the PM said at a union rally.
"I believe we can do it. This is not wishful thinking, it's a matter of looking at the maths."
