The already complicated life of Prime Minister Malcolm Turnbull is about to become harder, when South Australian senator Cory Bernardi stands in the Upper House to formally announce he is quitting the Liberal Party.

Barring any dramatic, late change of heart, he is expected to do that tomorrow, on the first sitting day of the new parliamentary year.

On one level it will change little: the Government won't fall, it will just add one more difficult negotiation to the Coalition's ordeal of getting bills through the Senate.

And it's not really a surprise, as Senator Bernardi has been signalling his intention to leave for a year, under the banner of his Australian Conservatives brand.

More deeply, Senator Bernardi's departure is yet another sign of the unravelling of the status quo in liberal democracies across the Western world.

The loss of faith in the old institutions of government and mainstream media is profound and may be permanent.

The immediate problem for the Prime Minister is that it will shake his already flimsy grip on his fractious party room.

There are others who believe Mr Turnbull is failing the tests of leadership and may use this opportunity to press their causes.

Turnbull could become more cautious to keep conservatives

First among equals is former prime minister Tony Abbott who, like Labor's Kevin Rudd, has refused to go quietly into the night.

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Although most believe Mr Abbott doesn't have the numbers to mount a challenge, his capacity to niggle, wound and distract the Government is undisputed.

There is also the possibility others might defect to the Australian Conservatives, or even One Nation.

The Government only commands the House of Representatives by a single vote and if a Coalition MP were to move to the crossbench, Mr Turnbull's already significant troubles would multiply.

All of this might make an already risk-averse Prime Minister even more cautious.

Rather than pushing him to embrace some of the media's favourite causes — such as a parliamentary vote on same-sex marriage and more action on climate change — it could well have the reverse effect.

Worried that more conservatives might quit the party, Mr Turnbull might opt to tread ever more carefully.

Senator Bernardi's decision to go also exposes the deep divisions in the Liberal Party, which threaten the future of Robert Menzies' fusion of liberals and conservatives. In the view of one minister, that alliance is "dying".

"What the Greens did to Labor is now happening to us," he told the ABC.

That view is buttressed by the latest Newspoll in The Australian, which shows that the primary vote of both major parties now parked in the mid-30s.

The Greens have permanently carved 10 per cent from Labor's left flank and a bevy of populists, such as One Nation, and Nick Xenophon have slashed the Coalition's share on the right.

Senator Bernardi has long predicted a people's revolution against politics as usual.

He was in the United States for three months last year and saw first-hand the insurgency of Donald Trump, which was above all else, a vote to smash the Washington consensus.

He is a social conservative and economic liberal who believes these forces can be harnessed, and he is the man to do it.

Bernardi faces challenge with Xenophon, Hanson

In that he will face stiff competition: South Australia already has a well-established, anti-establishment brand in Senator Xenophon, and Pauline Hanson would seem to have mortgage on those to the right of the Coalition — at least for the time being.

Research by both major parties and business shows the community is awash with feelings of uncertainty and a loss of control.

As the world becomes more complex and dangerous people are being drawn to strong leaders with black and white answers.

Add to that a loss of faith in almost every institution from the churches, through unions, business, the media and political parties, and the mood for change is deep. But to what?

It is impossible to predict where this fracturing of the status quo will land, but there are some very turbulent times ahead — and not just for Mr Turnbull.

The great skill of 20th century Australian politics was that it trod roughly a middle path, no matter which party was in government.

For all its many faults that system delivered a largely decent, successful, peaceful and moderate society.

The 21st century is showing early signs of being more extreme. And that should worry everyone.