Prime Minister Scott Morrison has pleaded with voters in Wentworth to consider the nation's economy when they cast their ballot at the by-election.

The Liberal Party is bracing for a historic loss in Malcolm Turnbull's former seat, vacated after Mr Turnbull was ousted as prime minister in a leadership spill.

Voters will head to the polls in the Sydney harbourside electorate of Wentworth this weekend.

AAP

The government's one-seat majority is under threat and the prospect of a hung parliament looms, with Liberal candidate Dave Sharma facing fierce competition from independent Kerryn Phelps.

"We have a strong economy, and this is what would be put at risk," Mr Morrison told The Weekend Australian.

"We can't put that at risk. This is the appeal we are making.

“Scott Morrison has got a lot to be held accountable for if they lose this, because he's handled this campaign appallingly” #WentworthByElection🗳 #auspol @SBSNews pic.twitter.com/wYhLduB2fO — Brett Mason (@BrettMasonNews) October 19, 2018

"I know people are angry about what happened, I get it. But we need to now put it behind us...it is now about something bigger than that."

But independent candidate Kerryn Phelps has emerged as the most likely threat.

READ MORE Former Liberal leader urges Wentworth voters to dump Coalition over climate inaction

The local doctor and Sydney city councillor is a social progressive who campaigned on same-sex marriage and advocates tougher action on climate change.

AAP

Labor candidate Tim Murray is the third major contender, with polls suggesting he could attract a similar primary vote to Dr Phelps.

Former prime minister Malcolm Turnbull’s caused some controversary on Thursday when his twitter account ‘liked’ a post that backed a “strong independent win” in Wentworth on Thursday - before quickly deleting it.

READ MORE Liberals staring down the barrel of Wentworth defeat

The original tweet was from a man who claimed to be “handing out policy info and how-to-vote cards for Dr Phelps”, who has emerged as the biggest electoral threat to the Liberals in the Saturday poll.

SBS News

There are a total of 16 candidates running in this week's by-election.