A by-election finished off last leader, remember?

Prime Minister Malcolm Turnbull and Minister for Foreign Affairs Julie Bishop speak to media after the official launch of the 2017 Foreign Policy White Paper yesterday.

Malcolm Turnbull has entered the danger zone, with every utterance from cabinet colleagues being viewed through a prism of leadership and positioning.

This is unsustainable and almost impossible to reverse for a leader whose authority is being openly challenged.

The risk for the Prime Minister is that if this is allowed to become the prevailing perception it can have only one outcome.

Julie Bishop’s intervention yesterday into supposed cabinet leaks — denying she was a leak and calling for an inquiry — was almost without precedent for a deputy leader. It was bizarre and rightly observed by colleagues as deliberate posturing. The insinuation was that Turnbull has lost control of his cabinet.

The apparent schism between Peter Dutton and Scott Morrison over religious protections has been no less subtle. The feud over same-sex marriage and the apparent divisions within cabinet over the threat of a banking inquiry have now become the proxy wars for the leadership.

The question is how long it can continue before coming to a head.

There are those in cabinet and the broader ministry who have come to their own individual conclusions that it’s over for Turnbull.

There is no collusion or conspiracy, no fix on numbers and certainly no assigned candidate, despite red herring tickets being floated, such as a Bishop-Morrison combination (which wrongly assumes Morrison would be interested in being a deputy).

There is now a more serious tone to the chatter that began two weeks ago. The view among the senior ranks of government is that the Bennelong by-election could become the catalyst.

In the unlikely, but possible, event that the seat is lost, Turnbull’s survival becomes deeply questionable.

Even so, with only one party room meeting left this year — the week before the by-election — the likelihood is Turnbull’s leadership woes will remain confined to chatter until at least the new year and until the citizenship crisis is resolved.

This means the government will continue to bumble along, with little prospect of clean air to resurrect an agenda let alone prosecute it with any effect.

“It’s stating the obvious but unless he can turn things around, you’d have to say it’s over,” another senior minister told The Australian.

“Bennelong is becoming increasingly likely to become a trigger if we lose it, or even if there is a swing of even 8 or 9 per cent.”

The irony would not be lost on Tony Abbott, who was toppled as leader the week of the Canning by-election.

Any objective assessment of the situation, considering the febrile nature of the party room, can only conclude that there are a growing number of MPs and senators who have given up on Turnbull but perhaps an equal number who hold out hope that things will change.

What will determine Turnbull’s survivability will ultimately come down to whether a left-wing Liberal leader can win seats in NSW and Queensland — rather than lose them — and not his failure to live up to the metrics he set for his own leadership.

It would be naive to suggest any Coalition member would willingly go into opposition in the belief it was more noble or virtuous than changing leader.