Malcolm Turnbull has admitted a loss in this weekend's federal by-election in Bennelong would place his government in a "very precarious" position.
Liberal candidate John Alexander will battle out Saturday's high-profile race against former NSW Labor premier Kristina Keneally.
Mr Alexander triggered the by-election after he resigned as Bennelong's MP over a dual citizenship issue.
If Ms Keneally could pull off an upset, it would rob the Turnbull government of its majority.
"Obviously we'd be down to 75 votes-all in the House of Representatives. It would be very precarious," Mr Turnbull told News Corp journalist Miranda Devine on her web-based show on Monday.
Ms Keneally has accused Mr Turnbull of alarming rhetoric amounting to "China-phobia" and "scaremongering", as both sides zero in on Chinese voters in the Sydney seat.
But the prime minister turned the attack back on Ms Keneally, who he says is trying to paint an unfair picture of him.
"Kristina Keneally I see is trying to play this up and suggest that I of all people am anti-Chinese. That just shows how desperate she is," Mr Turnbull said.
"If Kristina Keneally were to win in Bennelong not only would you be allowing her to do in Bennelong what she did in NSW, you'd be bringing Bill Shorten closer to the prime ministership."
The government has now lost 24 consecutive Newspolls, drawing closer to the 30 straight cited by Mr Turnbull as a reason for successfully challenging former prime minister Tony Abbott for the Liberal leadership.
"I do regret having said it only because it allowed people to focus on that, rather than substantive reasons," Mr Turnbull said.
He said the main issues which led him to mount a challenge were around economic leadership and governance rather than metrics.
Mr Turnbull refused to canvass the possibility of winning seats back from the opposition in subsequent by-elections if Labor MPs are referred to the High Court over their eligibility to sit in parliament.
