Rudd urged the party faithful not to give up hope, despite opinion polls showing the Tony Abbott-led conservatives as clear favourites to win the September 7 election.
"To those who say that Mr Abbott has already won this election, I say this -- never ever, ever underestimate the fighting spirit of the Australian Labor Party," Rudd told the party's major campaign rally in Brisbane.
"I have been in tougher spots before and come back from behind.
Rudd said he would "fight this election until the last vote is cast next Saturday night".
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"I believe we can prevail and I believe in the end we will prevail," he said.
Rudd took aim at Abbott's "priorities, judgement and temperament" in his speech, after the opposition leader described the conflict in Syria as "baddies versus baddies" in a television interview today.
The Rudd camp seized on the remarks, made as Australia prepares to assume the rotating presidency of the UN Security Council, as evidence Abbott was not ready for the international stage.
"I've yet to see a leader of a federal political party wanting to to be PM who would be this embarrassing when it comes to foreign policy."
However the latest opinion polls show the staunch Catholic and social conservative who once trained as a priest on track for a landslide win, with his Liberal-National coalition expected to pick up 86 lower house seats to Rudd's 61.
Despite the numbers both sides are promising a tight race to the finish, with Attorney-General Mark Dreyfus saying there were still large numbers of undecided voters to win over in the final week of campaigning.
It has left him struggling to sell the legacy of Labor's second term, much of which he spent on the backbenches.
Rudd has also allowed gripes about bias from Rupert Murdoch's Australian newspapers to become a distraction and, despite outperforming Abbott in at least two of the campaign's three leaders' debates, has scrabbled for traction.