Australia has two major political parties: the ALP (Australian Labor Party) and the L/NP (Liberal/National ) party. Roughly 70% of the population although for one of these two parties.
The remainder will vote for the GIMPs: the Greens, Independents and Minor Parties.
Like every other country in the world, Australia has a complicated voting system. On election day, Australian vote for your their first choice, then they number second, third, fourth, fifth choices, these are called “preferences” in Australia
This is why the GIMPs are so important. Roughly 30% of the population their first preference to the GIMPs but these are often not enough to get elected. You need 50% to get elected so GIMPs preferences are distributed until someone gets 50%. Usually this will be a member of the ALP or the L/NP.
In the long run, who forms government will depend on where the GIMPs preferences go.
You can see by this latest opinion poll, the the two major parties are relatively close: L/NP 34.5% and ALP 37%. The GIMPs share the remaining 28% and the distribution amongst them is relatively stable.

However, when all the GIMPs preferences are shared out between the ALP and the L/NP, they go 2:1 to the ALP.
With the two major parties so close together this graphic shows the impact of GIMPs preferences.

The final break down is ALP 56% to L/NP 44%. This would be described as a “commanding lead”
This means while the GIMPs will not get anywhere near the 28% representation they deserve in Parliament, their second and third preferences will determine who forms the next Federal government.
These two pictures must surely give the strategists in the major parties food for thought about where they should be aiming to win the swinging, the undecided, or the disaffected voters.