Many have tried, while some have had an impact not one has jumped the hurdle of voters in numbers big enough to power a true third way.
DLP, Greens both born in Labors ranks.
PUP Democrats and a host of small large L Liberals born from Liberal ranks.
Nationals? they too by their nature policies and voters numbers seem more than unlikely to even gain the support needed.
Time will surely bring another force to the front.
At this time my bet is it will be a small l Liberal party.
One that with the right leadership, can occupy the middle ground, and do well.
Voters want a middle path, every Labor government elected post 1975 promised that path.
Promised maybe not delivered, the next great one may well set new paths for future ALP as a party, right now my bet is a middle of the road Liberal party will come in the next decade

Posted this because I think it will take place, maybe soon.
Labor almost split, well in truth did, at the birth of the DLP, Catholic right of that party.
DLP for a while held the power to keep Labor out of office, but never the power to rule in its own right.
It could not bring the center, you must bring the center to govern.
Greens, unlike the DLP right, took our refugees to the left, and too fails still as it always will, to bring the center.
Nationals, as folks my age will know, had much more power under its country party name, Black Jack John Mcquain even stood in the way, for a time, of Billy McMarn becoming PM .
Then and now Nationals never had any chance of bringing the center with them.
One Nation and the right splinters from Liberals, too can not grow, they picked the very right,an area only few voters want.
So who will be the third force?
A Labor left split will die before it hits the ground
Labor evolution is moving towards the center, it has from 1983 onwards, but may well be beaten by a small l Liberal party that may be fueled by the upcoming election loss next year.
When formed it would be hard to defeat,Australians in numbers will always look for middle of the road policies not the edges

Dear Belly,

There is every indication brought about by the
extremists in the Liberal Party, that the Party
may split. And the next government looks like
being a Labor government. This will give time for
the Liberals no matter which faction to try to
reform and win the subsequent election - which would
correspond with what you're predicting.

I believe that Malcolm Turnbull was trying to bring
about some balance in the Liberal Party but was
constantly blocked by the extremists - with the
trouble-maker - Mr Abbott in the lead.

However, observing the trend in voter's reactions
the Independent element in our Parliament is a growing
force that will eventually have to be considered. And
perhaps that's where the roots of a "Third Force" really
lie - once they get united, the right leadership, and
better organised. People are looking for better government
which today's parties are unable to provide.

cont'd ...

Dear Belly,

What is missing currently in politics is the capacity
to manage any undertaking with the best advice and
knowledge from a diverse range of talent of the best
and the brightest in this country - to reach viable,
practical, and economic solutions. The problem is that
decisions are made with political agendas in place,
and are not necessarily governed by talent - to solve the
problems of the day. That's why the Independents who don't
have ties to political party agendas - have a better opportunity
to solve problems - if they get elected to govern.

Foxy agree with everything you said in full, Labor will win the next election.
Maybe not by the landslide it looks to be now, but after a storm of fake news and near slander it will win clearly.
Both sides agree the voters usually get it right.
This weekend Wentworth will be telling, every weapon he can lay his hands on has been used by ScoMo, he as I predicted has bought support back to the government.
Should the swing against them be more than about 7 percent it will be the death knell of his government.
People do not want the extremes, if they did on the left the greens would be twice the current size.
One Nation would out poll the National party.
We live at a time shifting left or right will not be rewarded with government
Voters want stability

Dear Belly,

I'm going to risk it and predict that the Liberals
will not win in Wentworth. I have more faith in
the voters there and the PM's recent promises
especially the one about his being "open" to moving
the Australian embassy to Jerusalem will not go down
well. It's an obvious attempt at vote-getting without
actually saying they will do it - and I
think the voters will see through it. Also you're right,
the voters do want stability - however the Liberals
currently are not able to offer that. They're too
divided.