On Monday’s episode of Q&A Malcolm Turnbull let slip on several occasions a demeanor of confected affability when questioning turned to contentious matters, including battles with the right of his party.

Given better polling news for the prime minister personally in the latest Guardian Essential poll that he’s closed a disapproval gap significantly you might have expected a more expansive, less combative Turnbull performance.

What then explains the prime minister’s tetchiness on Q&A, apart from fatigue at the end of a very long year politically?

One possible explanation is that Turnbull is in possession of internal Liberal party tracking polling in the suburban seat of Bennelong that indicates a closer contest than might have been anticipated a week or so ago.

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Earlier tracking polls – these measure voter attitudes on a daily basis – had been favorable for Liberal candidate John Alexander, but numbers appear to have tightened to the point where a loss cannot be excluded.

Lose Bennelong and thus a Coalition majority on the floor of parliament and Turnbull risks losing whatever momentum has been generated in the past week or so following the feel-good passage of the same sex marriage legislation, notwithstanding that a significant bloc of conservatives voted No.

A bad result would inevitably rekindle leadership speculation.

It should be noted here that highly multicultural Bennelong registered a narrow 50.2% No result in the plebiscite. That outcome is encouraging to Cory Bernardi’s Australian Conservatives.

Bernardi is making no secret of the fact he regards Bennelong as a touch-paper for his nascent movement. A good result will provide a useful recruiting platform for his party elsewhere, as he told me in his Senate office a week or so ago.

This brings us to Newspoll, published in The Australian today. While that poll is based on a fairly small sample of 527 voters and a margin of error in excess of 4%, its findings will be spooking Turnbull. These are bad, bad numbers for the Coalition.

The Bennelong poll records a collapse in the Liberal primary vote since the 2016 election when John Alexander secured 50.4% on the primaries.

Newspoll is reporting a 11% drop in the Liberal vote, and a corresponding 10.5% swing to Labor where its candidate Kristina Keneally has mounted a high-energy insurgent campaign.

Newspoll has Liberal and Labor candidates on 39% of the primaries.

What will be especially disappointing for the Coalition is that Keneally appears not to have been marked down for presiding over the dying days of a disastrous State Labor government.

With the Greens steady on 9% and the Australian Conservatives polling as much as 7% Bennelong will go to preferences. This may well prove a long night indeed for the candidate — and for Malcolm Turnbull.

Shorten, as might be expected, has been playing down expectations.

What has emerged as a significant imponderable in Bennelong is reaction of voters of Chinese origin to Turnbull’s clumsy attempts to make political capital out of Labor Senator Sam Dastyari’s contacts with Chinese billionaire political donor Huang Xiangmo.

The prime minister went further than he needed in his criticisms of Chinese political interference, thus risking a negative reaction from the biggest concentration of voters of Chinese origin in any electorate in the entire country.

While these aspirational voters may have chosen to make a new life in Australia, it cannot be assumed they are ill-disposed to the country of their birth.

Indeed many of these Chinese-Australians would probably regard the fact that China has “stood up’’ as a good thing.

Turnbull and his advisers might have consulted the 2016 Census for Bennelong before clumsily giving offence to a dominant ethnic group. In an electorate of 168, 948, 44,341, or 21%, identify themselves as being of Chinese ancestry.

Of that 44,341 more than half were born in China or in Hong Kong. These numbers are way above the national average. Bennelong’s 21% Chinese ancestry compares with a national average of 3.9%.

Turnbull’s minders should have been more careful before awakening a dragon.