Here’s a question at the beginning of what is scheduled to be the final parliamentary sitting week of the year (that is, unless debate over same-sex marriage legislation and citizenship issues spills over into next week):

Has Barnaby Joyce’s thumping byelection victory in New England (against little opposition) plus marginally better polling for the Coalition and, conversely, less good for Labor, provided a political circuit breaker for a beleaguered Prime Minister?

The short answer to that question is a heavily qualified “yes, maybe”.

These relatively positive developments for Malcolm Turnbull are a probably just a respite from unnerving events that have destabilised his government.

A bad result for the Liberal-National Party (LNP) in the Queensland state election on November 25 followed by mutinous criticism of Turnbull’s leadership — both on and off the record from within his own ranks — fueled an impression of a government in disarray, and one that was possibly unravelling.

Over the weekend, thanks to Joyce’s anticipated return to parliament to exert control over a chaotic National Party in revolt against Turnbull’s leadership, things have settled down – for the moment.

However, given the fluidity of politics these days almost anything is possible — including further revelations damaging to both sides about Chinese money politics — as a prime minister under siege struggles to get through to the end of the year without further mishap.

That is why the Bennelong byelection on December 16 carries serious risks for Turnbull. Will it turn out to be one of those inflection moments in Australian politics that have consequences far beyond the boundaries of the electorate itself?

In the Whitlam era, the Bass byelection in June 1975 provided just such a moment in which Labor lost a previously safe seat with a swing against it of 14.3%. This signaled the end was nigh for a chaotic government in its death throes.

As it happened, the seat was won for the Liberal Party by Kevin Newman, father of former Queensland premier Campbell Newman who knows a bit about wave elections that sweep incumbents out of office — and out of their own seat.

In the Howard era, the government was destabilised by the loss of the previously safe Brisbane seat of Ryan with a swing against it of 9.7%. That was in 2001 with Labor under Kim Beazley an electable alternative, and before the Tampa boat people episode scuppered Labor’s chances.

That 9.7% margin is precisely the hurdle former New South Wales premier and Labor’s Bennelong candidate Kristina Keneally will need to clear to provide a particularly unpleasant Christmas present for an unpopular Prime Minister.

More recently, the Canning byelection in Western Australia in 2015 — amid speculation the Abbott government might lose the seat — contributed to Turnbull’s own power grab.

He moved against Tony Abbott on the eve of the Canning poll, thus pre-empting the possibility that a reasonable result for the Liberal Party would bolster Abbott’s leadership.

In the event, the Liberal’s Andrew Hastie won the seat comfortably.

In other words, byelections in Australian politics have consequences, as we’ve seen in New England this past weekend.

If the Liberal Party loses Bennelong for the second time in a decade (John Howard lost the seat and government in 2007) the rats and mice in conservative ranks will continue to gnaw away at Turnbull’s leadership.

On the other hand, if the Liberals win comfortably and Labor performs poorly, the result will rebound on Opposition Leader Bill Shorten who has gambled on an upset in a seat that should notionally remain in Coalition hands.

Now, a word about the latest polling: two national polls were out this morning that will provide some comfort for Malcolm Turnbull and give pause to a Labor party on the attack.

No doubt Labor had hoped a chaotic aftermath to the Queensland poll would further drive down support for the Coalition, but this has not transpired. Both Newspoll, published in The Australian, and Ipsos in the Fairfax papers, indicate some steadying in the government’s position.

Importantly for Turnbull himself Newspoll shows he retains a lead over Shorten as preferred prime minister, 39-33%. However, what should be concerning both major parties is that their primary votes remains in the doldrums.

In the Ipsos poll the Coalition and Labor dipped to 34% and 33% respectively. In Newspoll the Coalition was up two points to 36% from 34% three weeks ago. Labor was down one point to 37%.

These are the numbers to which the professionals pay most attention. On that basis Turnbull and the government remains in deep trouble with Newspoll reporting a two-party preferred margin to Labor of 53-47%, and Ipsos the same. If those numbers held for a general election the Coalition would shed more than 12 seats, but the point should be reinforced that much can — and will — happen before a poll is due by 2019.