Scott Morrison and Bill Shorten have cast their votes along with millions of Australians across the country in a poll that is tipped to see Labor form the next federal government.
The final Newspoll of the campaign has Labor ahead of the coalition 51.5 to 48.5 on a two-party preferred basis, while the latest Ipsos poll shows Labor in front 51-49.
If accurate, Labor would make a net gain of 12 seats, giving it 81 MPs in the 151-seat parliament.
A confident Mr Shorten was handing out how-to-vote cards at his local polling booth in the Melbourne seat of Maribyrnong, before voting himself.
"We will shake up politics and get on with climate action," the opposition leader told one supporter.
He later told reporters that if elected he would aim to get his cabinet sworn in as early as next week.
The prime minster, meanwhile, made a frantic last effort to hold power, visiting the Tasmanian seats of Braddon and Bass before returning to Sydney to vote in his own seat of Cook.
""I make no assumptions about tonight," he told reporters after casting his vote.
Nationals Leader Michael McCormack holds a safe margin of 16 per cent in his regional NSW seat of Riverina, but he is taking nothing for granted in his constituency or those of his National colleagues.
"I'm worried about all of them. Only with a National Party member there, are the regions going to be best represented," Mr McCormack told ABC news after voting at the South Wagga public school.
Greens Leader Richard Di Natale was working a booth in the Victorian seat of Higgins where government minister Kelly O'Dwyer is retiring.
He is hoping for a strong Greens presence in the Senate and picking up lower house seats like Higgins and Kooyong.
"Whoever forms government... the first order of business is taking strong action on climate change, having a plan to transition away from coal," Senator Di Natale told ABC news.
The Australian Electoral Commission said about 4.76 million votes had been cast at early-voting centres, with 700,000 votes cast on Friday.
This compares to a total of 3.2 million at the 2016 federal election.
Mr Shorten said pre-polling is convenient, describing it as the "Uber factor".
"But I also believe there's a mood for change. You don't have record numbers being set, people rushing out to save the government," Mr Shorten told ABC news.
But Home Affairs Minister Peter Dutton said what he picked up from the booths during three-weeks of of pre-polling in his Queensland seat of Dickson was nothing but anger against Mr Shorten and his planned tax changes.
"People were waiting for Bill Shorten with baseball bats," Mr Dutton said after voting in his northwestern Brisbane seat.
It has been described as a nasty campaign, but former prime minister Tony Abbott said it sank into "the sewer" when one of his supporters in the Sydney seat of Warringah was stabbed with a corkscrew on Friday night.
"My message is that the voters of Warringah should not reward this kind of really low and vicious behaviour," he told reporters.