Alex Turnbull rejects claims he's acting on behalf of his father in Wentworth

The son of former prime minister Malcolm Turnbull has rejected the suggestion he could be acting on his father's behalf by campaigning against the Liberals.

Alex Turnbull, right, has responded to claims he's acting on behalf of his father ahead of the Wentworth by-election. Source: AAP

The son of former prime minister Malcolm Turnbull says he is not acting as a proxy for his father by campaigning against the Liberal Party in his former electorate.

"Absolutely not," Alex Turnbull told ABC Radio of the suggestion on Monday.

The son of the former Liberal leader is backing Labor candidate Tim Murray in a crucial by-election in Wentworth, the Sydney seat his father relinquished when he was dumped as prime minister in August.

The son of former PM, Malcolm Turnbull says he's not his father's proxy. Source: Facebook @Alex Turnbull

Liberal Dave Sharma and independent Kerryn Phelps are also vying for success when voters hit the polls on Saturday.

Alex Turnbull said he didn't seek his father's permission for his anti-Liberal campaigning and would not have received it if he had.

But he is determined to send a message to the Liberal Party about its stance on energy and climate policy.

"What I am very motivated by is to point out the unreality and the absurdity that we're still having this debate when technology has made it possible to just get on with it," he said.

The younger Mr Turnbull said he was concerned the Liberal Party is following in the lead of the Republican Party in the US.

"My concern is I see a similar pattern where culture wars are taking precedence over good, sober, sensible policy," he said.

"That's why I've come out so strongly because when I speak to my friends in the states, they say 'wow, I wish I'd spoken up earlier' because we're stuck with this now."

Mr Turnbull, who lives in Singapore, said he wouldn't consider representing the Liberal Party as it now stands.

But he would consider the idea if the party underwent reform.

Candidates for Wentworth by-election at a community forum: Dave Sharma, Dr. Kerry's Phelps, Tim Murray, Dominic Wy Kanak and Licia Heath. Source: AAP

"It's something I would consider if basic things, like ensuring the National Party isn't infiltrated by Nazis, was solved," he said.

"There's some basic things which need to happen I think for that party to be acceptable to a lot of normal, acceptable people."