A Fairfax Media-ReachTEL published on Thursday revealed Ms Keneally trails Liberal candidate and former MP John Alexander in the all-important two-party preferred vote 47 per cent to 53 per cent.

Mr Alexander's primary vote has dipped slightly, from 41.6 per cent on November 17 to 40.4 per cent on December 12, while Ms Keneally's has climbed from 34.5 per cent to 35.7 per cent; just 2.4 per cent of voters now say they are undecided, a drop from 8.3 per cent.

If Ms Keneally were to defy expectations and win Bennelong for Labor, Prime Minister Malcolm Turnbull would lose his majority in the Parliament, placing his government in a more precarious position.

In addition, Labor and the crossbench would have the numbers to team up and refer government MPs to the High Court, as they attempted to do in the last sitting week of the year.

But in an interview on Sky News, the network she worked for until recently, Ms Keneally was asked three times if she was prepared to rule out taking the NSW senate seat that will soon be vacated by Senator Dastyari, who resigned following revelations in Fairfax Media over his links to Chinese Communist Party-linked political donor Huang Xiangmo.

She repeatedly declined to do so to rule out the move. Labor insiders in NSW believe she is the front runner to take the seat if she wants it, though a number of candidates such as United Voice union leader Tara Moriarty and the Lowy Institute's Michael Fullilove have also been mentioned as possible candidates.

"I'm only here to fight for Bennelong, that is all I'm doing, the only job I have been offered is the opportunity to be Labor's candidate for Bennelong," she said.

"And as I've said before, I've been offered Senate seats before and turned them down. This is all I'm focused on, Bennelong, no one has offered me the job and I haven't had any conversations about it."

"You can ask me any way you want, I'm not ruling anything in or out after the polls come in on Saturday night. I gave up my my job at Macquarie university to run for this position, I've gone on leave without pay at Sky News, I'm not even contemplating what happens after this byelection."

The battle for Bennelong has become a bare-knuckle fight, with the major parties trading blows and making claims and counter-claims about health care funding cuts, damage being done to the China-Australia relationship by proposed foreign interference laws and Ms Keneally's links to disgraced Labor figures such as Eddie Obeid.

Ms Keneally claimed voters in the seat, which has large Chinese-Australian population, were alarmed by the Prime Minister's rhetoric about China and suggested it was "not conducive to a harmonious Australia".

He had, she added, "decided to score political points in this Bennelong byelection, to put at risk the good harmony that exists here in Bennelong, to put at risk our economic trading relationships with China, to put at risk the important flow of students that come to our universities" with his political attacks on Labor and on Senator Dastyari.

Mr Turnbull dismissed Labor's claims of his "China-phobia" as "desperate and absurd".

"To suggest that somebody whose granddaughter is one of those one million Australians of Chinese ancestry, is anything other than a friend of Chinese people is absurd, completely absurd," the Prime Minister said earlier this week.