Already boasting nine upper house seats, they could add to that tally in Queensland, New South Wales and South Australia, while inner-city Brisbane and Melbourne seats such as Griffith, Brisbane, Higgins or Macnamara appear their best chance in the lower house.

Their only current lower house MP - leader Adam Bandt - looks certain to retain Melbourne, and left little doubt as to which party he thought would form government.

"One more sleep until we talk about former prime minister Scott Morrison, and I'm feeling pretty good about it," he told reporters.

"We are hoping to grow in the Senate, to gain additional senators and be in balance of power and be the largest third party in the Senate ever.

"But we're also in the race, and in front I think, in a few lower house seats around the country as well."

Mr Bandt said the party would use the balance of power to push for real climate action.

The Greens have also campaigned promising to address cost of living by including dental and mental health care in Medicare, to build a million affordable homes and make child care free.

"This election has turned into this really narrow contest between a terrible government that's got to go and an opposition that keeps agreeing with them on too many of the issues that matter," Mr Bandt said.

"While the others have gone small, the Greens are tackling the big issues like climate change, like making housing affordable, and tackling the inequality crisis ... (our plans) can be funded by making the billionaires and big corporations pay their fair share of tax and without asking everyday people to pay more."

Australian Associated Press