Peter Dutton says he is comfortable with the result in the Aston by-election being a test of his political leadership.
Senior Labor figures campaigning in the seat have routinely mentioned a swing against the Liberals in the seat being a "threat" to the opposition leader.
One Labor campaign slogan describes Mr Dutton as "leader of Morrison's Liberal leftovers".
Mr Dutton, who is campaigning in the Victorian seat with the Liberal candidate Roshena Campbell on Wednesday, said he expected the result to be close.
"In a by-election, people know that they're not going to change the government - so there is a greater focus on the local candidate," Mr Dutton told ABC radio.
"The government's in its first year, so it's still in its honeymoon as well.
"It'll be a verdict on the leaders, no question about that, and it'll be a verdict on the campaign that both the Liberal Party and the Labor Party run on the ground.
"I'm happy for it to be a verdict on all of those things."
Mr Dutton said voters would see through Labor's attacks on him as leader.
"I think we've been a constructive opposition," he said.
"The Labor Party will continue to throw mud at me and that's fine, but I think people can see through that and I'll let people make their own judgements.
"But, ultimately I think, the bigger focus in a by-election is on the local candidate and the local campaign, and I think we've got the better candidate, I think we've got the better campaign."
No government has won a by-election off an opposition in over 100 years.
The seat is being vacated by retiring former Liberal minister Alan Tudge.
Labor's candidate is union official Mary Doyle.
