It's the nightmare scenario for many politicians out on the campaign trail: An inconclusive result that sends the major parties into brutal negotiations with a handful of new crossbench MPs.
If there is no clear majority after the ballots are counted, the outcome of the election is deemed a 'hung parliament'.
That's one where either the Coalition or Labor must seek an agreement with the rump of a minor party or any independent MPs that will be sitting between them in order to govern.
For the Coalition, losing even a single seat would require them to seek a deal with crossbench MPs to govern in a minority government.
While polling has pointed towards a decisive Labor victory, that could also result in a hung parliament if the swing doesn't go their way in a few key seats.
The major parties obviously want to govern in their own right and will often portray a minority government as a poor outcome.
However, there are plenty of people who believe hung parliaments can be a good thing for the country.
What is a hung parliament?
In the 151-seat House of Representatives, Labor or the Coalition (the name for the alliance of Liberal and National MPs) must win at least 76 seats to govern in their own right.
Any less and they must seek the support of MPs outside their party.
Usually, that means guaranteeing what is called "confidence and supply" from those MPs, a promise that they will support the government in any votes on its legitimacy and the passage of budget bills to allow the government to continue functioning.
The concern for governments running the country as a minority is that every controversy is heightened as a threat to their continuing existence, as the loss of a single MP could spell the end of their term in power.
Back in 2010, a hung parliament resulted in Labor striking a formal agreement with the Greens that required weekly meetings with the party to discuss the government's legislative agenda, as well as undertakings with three independents in exchange for their support.
The deal also resulted in a reversal of Ms Gillard's promise not to introduce a price on carbon, a moment that many have come to associate with a hung parliament scenario.
That term of government was marked with constant leadership speculation and perceptions of instability, though much of that related to division within Labor's own ranks.
Still, the Coalition has sought to capitalise on memories of that time as a pitch to stick with them and not to vote, in protest, for high-profile independents.
This time around, both parties have been eager to make clear that they would not do deals with the Greens if they could not win a majority — whether that actually holds in a hung parliament scenario would remain to be seen.
Who is prime minister in a hung parliament?
The prime minister in a hung parliament is the leader of whichever party secures support from the crossbench to form government.
That will always be one of the major parties.
Is a hung parliament good?
Despite perceptions that former prime minister Julia Gillard's term was unstable, her minority government managed to pass more than 560 pieces of legislation — more than the preceding Rudd government and more than John Howard when he controlled both houses of government between 2005 and 2007.
Whether the passage of that legislation was good or bad depends on your politics, but it shows that minority government is not necessarily a barrier to legislating.
In fact, governments normally have to negotiate to get their agendas through parliament anyway and neither party has held a majority in the senate since 2007.
The complication for a minority government is that the people whose support they need in the lower house may not have the same opinions as those they need in the upper house, making it harder for them to fulfil their agendas.
And voters who cast a ballot for Labor or the Coalition on the expectation they would deliver a certain policy may be upset if the government changes those policies in negotiations to form government.
However, veteran MP Bob Katter (Katter's Australian Party) last month pointed to comments by Anthony Albanese himself as to the benefits of a minority government.
"There is a great quote in the parliament … it was from Albanese, and he said: 'We got every single piece of legislation through, and we were a minority government'," Mr Katter recalled.
“Why did we get it all through? Because we had to convince people that it was the right thing to do. We got it through because we had to convince people.
"If we couldn’t convince them that it was the right thing to do, then we didn’t move the legislation. There is a name for that, and it’s called democracy.”
Greens MP Adam Bandt said the 2010 minority government also allowed issues that otherwise might have been missed to get attention.
"I got a bill through to give protection for firefighters who were contracting cancer and [a hung parliament] made it easier for them to do that," he told the National Press Club this week.
"That's the kind of thing [that happens] when you have the systems in place that allow third voices to get the issues on the agenda that the others don't want to touch, and then progress them through the parliament."
A majority government is not necessarily stable, either, as a decade of leadership spills and as, more recently, government MPs voting down their own legislation has shown.
Prime Minister Scott Morrison, however, has argued that kind of instability would be an almost daily occurrence in a minority government.
How likely is a hung parliament this time?
ABC chief elections analyst Antony Green said that, if the polls were correct this time, he expected the result would not end in a hung parliament.
"If the overall polls are right, and Labor is on about 53 per cent of the two-party preferred [vote], I wouldn't expect there to be a hung parliament, if that is the result," Mr Green said.
"If [the margin is] narrower, it's possible.
"It will then come down to who has got more seats. Crossbenchers would always prefer to support the party with more seats."
One wild card this election is the number of high-profile and well-funded independent candidates running in ordinarily blue-ribbon Liberal seats.
Their own polling suggests many have a chance of unseating established politicians, but it will not be clear how many — if any — will get up until vote counting is complete.
If the result ends in a hung parliament, Mr Green said that, as a general rule, the negotiations to form government would not be settled until after all the votes were counted, meaning it would likely take at least a fortnight before Australia learned who would be governing for the next three years.
