Australians are heading to the polls to select their next parliament and prime minister, in what has been widely referred to as the climate-change election.
Some 16.5 million Australians are enrolled to vote on Saturday, with more than four million having already cast ballots in early voting by Thursday afternoon.
Polling stations will be open between 8am and 6pm local time (22:00 GMT on Friday - 08:00 GMT on Saturday). The winner for the lower house, which forms the government, is expected to be known either by late on Saturday or the early hours of Sunday.
Observers say it is the most ideological election Australia has seen in years, with Prime Minister Scott Morrison emphasising the differences on economic policy between his centre-right Liberal-National Coalition and the "reckless spending" of his main rival, the centre-left Australian Labor Party led by Bill Shorten.
"The major campaign themes have been climate change and the economy, specifically whether it is delivering for people," said Danielle Wood, programme director at the Grattan Institute, a Melbourne-based think-tank.
"There is a big difference between the major parties on both these areas."
Morrison insists it will be a close election. To win a majority in the House of Representatives, either major party will require 77 seats. The Coalition currently holds 73 seats, while Labor has 72.
If no party emerges with a clear majority, they will need to negotiate with the cross bench for support to form a government. Both main parties are expected to seek the backing on independents, with Labor likely to accommodate any MPs from the left-wing Greens, the country's traditional third political force.
Online bookmaker Sportsbet is tipping a win for Shorten - paying just 1.14 Australian dollars ($0.78) for Labor to be "sworn in government". The incumbent Coalition, which has consistently trailed in opinion polls for more than a year, is paying 5.75 Australian dollars ($3.95) if it can pull off a victory.
On Friday, the broadsheet newspapers in the country's two largest cities - the Sydney Morning Herald and The Age in Melbourne - endorsed Shorten as the best chance to end a "cycle of instability" in Australian politics.
The country has had six changes of prime minister over the past 12 years - mostly the result of internal party fights.
"There is absolutely no question that people are hugely frustrated by the revolving door of prime ministers," Wood, of the Grattan Institute, said.
"Labor has tried to capitalise on this by campaigning around the government's chaos and trying to use it to call Scott Morrison's trustworthiness into question."
But Wood noted that this has affect both main parties, noting that minor parties could benefit from a "strong protest vote looking for a home".
Mining billionaire Clive Palmer has boasted $60m for his United Australia Party's campaign which promises to "make Australia great".
Palmer's party could steal votes from Pauline Hanson's One Nation, a far-right, anti-Islam party recently embroiled in scandal, partly as the result of an Al Jazeera investigation which revealed it had tried to garner support from pro-gun groups in the United States.
The left-wing Greens, meanwhile, seem likely to benefit from voters wanting decisive action on climate change - which recent polls have shown is the number one issue for much of the population.
In the lead-up to the vote, ex-Liberal Prime Minister Tony Abbott and the Minister for Home Affairs Peter Dutton have both been targeted by progressive lobby group GetUp.
Abbott has held his seat of Warringah in Sydney's affluent Northern Beaches since 1994, has been criticised for his conservative positions on climate change and social policy.
Zali Steggal, a lawyer and former Olympian, is campaigning against Abbott on climate policy and could drive a significant swing against him, positioning herself as an economic conservative.
Meanwhile, the Liberal-held east Melbourne seat of Chisholm will make history, with both major candidates being Chinese-Australian women.
Whoever wins - Liberal candidate Gladys Liu or her Labor opponent Jennifer Yang - will represent the country's first Chinese-Australian female member of parliament.