Australia's bitterly divided Parliament will declare a truce today to hear Prime Minister John Key try to steer the transtasman relationship to a new level.

Mr Key will join a handful of influential world leaders when he becomes the first New Zealand premier to address the federal Parliament, taking advantage of a peak in goodwill between the two countries.

But behind the amity of his brief visit to Canberra and Sydney, Australian politicians will be focusing on a battle for survival as his Australian counterpart, Julia Gillard, struggles to keep her head above the deluge.

Mr Key arrives in a city gripped by Ms Gillard's spectacular plunge in the polls and her furious struggle to impose carbon and mining taxes and find a viable solution to the endless political minefield of asylum seekers.

Although he faces his own election in November, Mr Key's problems have nothing on those facing Ms Gillard, whose fellow-feeling for New Zealand has helped cast a new, rosy glow across the Ditch.

The steep decline of her fragile minority Government since its return to power last year was further confirmed yesterday in a Newspoll in the Australian, which shows that core support for Labor is lower than when predecessor Kevin Rudd was deposed.

In the past two weeks the Opposition has widened its lead over the Government to 55 per cent or 10 points in the two-party preferred vote that determines elections. And while neither is popular with voters, Opposition leader Tony Abbott has narrowed Ms Gillard's lead as preferred prime minister to just three percentage points.

But even with this mountain of trouble, she has still made time for New Zealand and Mr Key, an affirmation of her view of the relationship.

Australia has been deeply moved by the disasters that have overtaken New Zealand - especially since the February earthquake - reflected both in the assistance rushed across the Tasman since the Pike River mine explosion and the presence of Ms Gillard, Mr Abbott and Governor-General Quentin Bryce at the earthquake memorial in Christchurch.

The nation also warmed to New Zealand's response to Australia's summer of floods and disasters.

Ms Gillard overrode bureaucracy to provide federal relief payments initially refused to expatriate New Zealanders hit by the Queensland floods, and declared donations by Australians to the earthquake appeal to be tax-deductible - a first for the nation.

Mr Key's address to Parliament is regarded by New Zealand officials as an unprecedented opportunity to keep Australia's political mind on the transtasman relationship. Its contents have not been disclosed, but it is expected to emphasise the strength of the relationship and its mutual benefits, confirm that despite disasters New Zealand remains open for business, and to focus on future potential.

Mr Key will also talk with Ms Gillard and senior ministers, likely to include Treasurer Wayne Swan, Defence Minister Stephen Smith, Foreign Minister Kevin Rudd, Attorney-General Robert McClelland and the ministers for trade, climate change, immigration, and innovation and science. He will also meet Mr Abbott.

Talks are expected to cover issues including Afghanistan, the Pacific - especially Fiji and the Pacific Islands Forum - people smuggling, closer economic relations, the Trans-Pacific Partnership and October's Commonwealth Heads of Government Meeting in Perth.

In Sydney Mr Key will attend an earthquake appeal fundraising dinner.