Australian Prime Minister Kevin Rudd vowed on Sunday to fight until "the last vote is cast" in a rousing speech declaring himself the "comeback kid for Australia", a week away from national polls.

Rudd - who was dumped as prime minister by his own government colleagues in 2010, only to regain the top job in a similar leadership wrangle in June - urged his Labor Party faithful not to give up hope, despite opinion polls showing the Tony Abbott-led conservatives as clear favorites to win the election on Saturday.

"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 its major campaign rally in Brisbane.

"I have been in tougher spots before and come back from behind.

"As one young kid said to me the other day - 'Kevin, we want you to be the comeback kid for Australia'."

Rudd said he would "fight this election until the last vote is cast next Saturday night".

Rudd officially launched his center-left party's campaign in his hometown of Brisbane on Sunday. It is the capital of Queensland, a battleground state for swing seats that will decide the election.

The opposition has framed the election as a referendum on the carbon tax paid by Australia's worst greenhouse-gas polluters, which Abbot has promised to abolish.

Rudd's government argues the election is about the "wrong priorities" a conservative government would implement, including a policy of paying mothers up to A$75,000 ($66,750) for six months' maternity leave regardless of how wealthy they are.

Labor has ruled for almost six years under the leaderships of Rudd and the deputy who replaced him for three years, Julia Gillard. Rudd said the end of an Australian mining boom demands new policies that only Labor can provide to diversify the slowing economy.

Among election promises announced on Sunday, Rudd said a Labor government would increase tax deductions that 3.2 million small businesses could claim on equipment investment. The pledge would cost the government A$200 million over four years in lost tax revenue.

The government would also create between A$156 million and A$624 million in additional work for Australian industry a year by legislating to ensure that infrastructure projects worth more than A$300 million engage more local contractors.

The government is under fire over debt created by stimulus spending that kept Australia out of recession during the global economic crisis.

While polls show Rudd remains a more popular choice of leader than Abbott, Labor's popularity lags below that of the opposition coalition.

Rudd's return to the leadership after his party dumped Gillard brought a surge in Labor's polling, but Rudd has failed to maintain that momentum through the campaign.

Rudd has blamed negative coverage from News Corp, which owns 70 percent of Australia's newspapers.

Sydney's The Sunday Telegraph, Australia's largest circulating newspaper which is owned by News Corp, filled its front page with a photograph of Abbott and the headline "Australia Needs Tony".

"It seems an understatement to observe that the Labor-led government of the past six years has been a grave disappointment," the newspaper's editorial said.

"Another three years of Labor would be an unmitigated disaster," it added.

AFP-AP