Labor appears on track to defeat the Morrison coalition government, with counting underway in most parts of Australia.
Voting is now closed in the eastern states and South Australia and the Northern Territory. Western Australia booths will close at 6pm local time (10pm NZT).
The Australian Electoral Commission has begun counting votes, which include more than 4.7 million of the 16 million Australians enrolled to vote cast their ballots before polling day.
A Nine exit poll today has given Labor a 52-48 two-party preferred lead over the coalition, which could deliver it as many as 82 seats in the 151-seat lower house.
The Liberal-National coalition's primary vote sat at 39 per cent, just one point ahead of Labor, with the Greens polling 10 per cent and "other" at 10 per cent.
Labor deputy leader Tanya Plibersek said the party, which went into the election with 69 seats, had "high hopes" to pick up 12 seats it had been targeting.
"I feel positive. I feel like we are ahead but I am more cautiously optimistic than confident," she said.
Former Liberal deputy leader Julie Bishop, who retired at this election, said there was a "path to victory" for the coalition and it would be a "night of surprises".
The exit poll also showed voters favoured Ms Bishop to lead the Liberals, with 30 per cent rating her, 27 per cent for Scott Morrison, 17 per cent for Malcolm Turnbull and four per cent for Home Affairs Minister Peter Dutton.
Ms Bishop said Mr Morrison could not be criticised for the quality of his campaign and the party would never know what the result would have been under her leadership.
"This reminds me of day 33 of the campaign when the late great Doris Day was quoted as saying 'Que sera sera' (whatever will be, will be)," Ms Bishop said.
Nationals deputy leader Bridget McKenzie said it was not about a national swing but individual seats.
Victorian Labor MP Richard Marles said he's been watching the tightly-fought campaign in the seat of Corangamite, which is next to his seat of Corio in Geelong.
"My working assumption has been if it's a contest in Corangamite it's a contest around the country. I think the election's going to be a close call tonight."
The Nine exit poll found the biggest state swing would be 3.2 per cent to Labor in Victoria.