By Kaaren Morrissey and Rachael Ward

THE LNP candidate for the federal seat of Fadden vying to replace former coalition minister Stuart Robert says voters are focused on cost-of-living issues.

Cameron Caldwell, who is the favourite to win the by-election in the northern Gold Coast electorate, cast his vote with his wife, Lauren, at a polling booth on Saturday morning.

Asked if Mr Robert’s involvement in the robodebt scandal that engulfed the previous Liberal-Nationals federal government was impacting voters, he said they have other things on their minds, like cost of living and crime.

“Those are issues that are really starting to bite in their households and it’s whether people can put food on the table and keep the lights switched on,” he told Sky News.

“That’s really what’s on their mind as they walk into the polling booth today.”

Under Mr Robert, whose resignation from parliament in May triggered the by-election, the LNP held the seat with a margin of 10.6 per cent.

Robodebt is the name given to an unlawful debt recovery program that saddled almost half a million welfare recipients with hundreds of millions of dollars in false Centrelink debts between 2015 and 2019.

A royal commission investigation into the scheme released earlier this month laid the blame at the feet of senior public servants and coalition ministers including Mr Robert, Scott Morrison, Alan Tudge and Christian Porter.

Labor has tried to use this to bolster its candidate for Fadden, Letitia Del Fabbro, who says any swing to her would be a blow to the coalition in one of their safest seats.

She said cost of living had dominated the campaign and running had been a fun opportunity to get members together.

“Any swing against the LNP would be a loss to them,” Ms Del Fabbro told reporters on Saturday.

Treasurer Jim Chalmers said the average swing against a government in a by-election was about four per cent so anything less would be embarrassing for Opposition Leader Peter Dutton.

“Our expectations are tempered, but we couldn’t have put forward a better candidate and we’re focused on the issues that matter to people here,” Dr Chalmers said after handing out how-to-vote cards.

Labor has won Fadden only once, which was in 1983 under the election of the Hawke government.

Prime Minister Anthony Albanese said he wasn’t expecting a result like the historic Aston by-election, which the government claimed earlier this year after the resignation of former coalition minister Alan Tudge.

“That was an extraordinary result the first time in 100 years that the government have won a seat off the opposition,” he said on Friday.

A total of 13 candidates are running in Fadden including from the Greens, Pauline Hanson’s One Nation and the Australian Democrats.

Mr Robert served as the veterans’ affairs, national disability insurance scheme and government services ministers under the Turnbull and Morrison governments.

Dutton faces a boost or a blow from Fadden