Nationals MP Darren Chester on Friday stated bluntly: "I don't think the result is going to be good for us in Wentworth."

"I think it's important to remember how we got to Wentworth," Mr Chester told ABC radio while being quizzed about a potential Nationals leadership spill.

"I don't think the Wentworth by-election will be good for the government. I think we're about to get a real-life opinion poll on what Australians think of political parties that undermine their leaders and change leaders mid-stream."

Mr Morrison says there's a lot at stake in Wentworth on Saturday with internal Liberal polling suggesting independent Kerryn Phelps could beat the party's own candidate Dave Sharma.

The bookies have now installed Dr Phelps as the firm favourite at $1.33 with Mr Sharma out to $3.

Asked if he's praying for a miracle in the Sydney seat - vacated by Malcolm Turnbull after he was knifed in August - the prime minister said: "I pray often about many things."

"This is a very important by-election, " Mr Morrison told the Seven Network.

"The lead independent candidate Kerryn Phelps on multiple occasions couldn't even say she'd support a confidence motion.

"That can throw the entire government into a lot of uncertainty. I know there's been a lot of instability and uncertainty but voting for an independent will only make that worse."

Mr Morrison later insisted Mr Sharma would be just as good as the dumped Mr Turnbull.

"I was there when it was happening, supporting the then-prime minister when they were seeking to take him down," he told voters while campaigning in Bronte.

"(But) what I'm telling you is this candidate for Wentworth will be as good as the last one. He's the same calibre."

Mr Sharma, a former Australian ambassador to Israel, is running on 45 per cent of the two-party preferred vote compared to 55 per cent for Dr Phelps, internal polling leaked this week suggests.

The Liberal candidate has had a difficult final week of the campaign as the government lurched from one mini-upset to the next.

Canberra flagged moving the Australian embassy in Israel from Tel Aviv to Jerusalem on Mr Sharma's advice; embarrassingly the government's own senators voted in favour of a One Nation motion stating "it's OK to be white"; and there is talk of a Nationals leadership spill.

Mr Sharma also had to condemn a "despicable" anonymous email circulating in the electorate falsely claiming Dr Phelps was pulling out the race because of a HIV diagnosis.

Mr Morrison countered with new data showing Australia has recorded its lowest jobless rate in seven years; the passage of laws delivering tax cuts to small and medium-sized businesses; and ratification of the Trans-Pacific Partnership trade pact.

But deputy opposition leader Tanya Plibersek says Mr Morrison doesn't share voters' values.

"They voted overwhelmingly in support of marriage equality - the prime minister didn't."

Australian Associated Press