Labor has dismissed the former SAS soldier running for the Australian Conservatives in the federal seat of Batman as a "minor party candidate".
Kevin Bailey is standing against a political "drift to the left" in the March 17 by-election for the marginal, progressive inner-Melbourne seat which Labor is fighting to retain.
His nomination comes after the Liberal party confirmed it would not run a candidate, leaving the field open to Labor to try to hold the marginal seat against the Australian Greens.
"With your help, Australian Conservatives can stand strong in Batman and make sure our nation does not continue its drift to the Left," Mr Bailey said in a statement released to party members.
Union boss Ged Kearney is Labor's candidate, while the Greens have chosen Alex Bhathal for the contest sparked by the resignation of Labor's David Feeney because of his dual citizenship.
Mr Feeney won Batman in 2016 in a tight contest against the Greens, on the back of Liberal preferences.
Ms Bhathal has unsuccessfully contested the seat in five elections.
Senior Labor frontbencher Anthony Albanese visited the electorate on Tuesday and appeared unfazed by Mr Bailey's tilt at the seat.
"There's always going to be some minor party candidates in the election," he told reporters.
"There's no doubt in a by-election votes tend to spray around and minor parties will get votes."
The Australian Conservatives are led by former Liberal Cory Bernardi, who remains a senator for South Australia.
The party was set up in response to concerns amongst right-leaning Liberals the federal Liberal party was abandoning its conservative roots.
Party spokesman Lyle Shelton told members the fact that the Liberals aren't running in Batman was "all the more reason for us to give the people of Batman the chance to send a message to Canberra".
Mr Bailey was a SAS soldier before taking up a career as a financial planner and is a former Herald-Sun columnist.
Mr Albanese slammed the Liberal party for failing to field a Batman candidate.
"The Liberals in not running are showing their hand - I guess they've given up on being a government at the moment so I guess it's consistent with that," he said.
