The Australian Greens are hopeful of seizing a second House of Representatives seat following the announcement the Batman by-election will be held on March 17.
Speaker Tony Smith told parliament on Wednesday he had issued a writ for the by-election, triggered by the resignation of Labor MP David Feeney over his dual citizenship.
Mr Feeney has decided not to run and Labor has selected union boss Ged Kearney as its candidate.
Electoral rolls will close on February 14 and nominations are due by February 22.
The Greens have selected Alex Bhathal, who unsuccessfully contested the seat in five elections.
Ms Bhathal secured the highest primary vote in Batman at the 2016 election, but Mr Feeney scraped over the line with Liberal preferences.
The Greens currently have only one lower house seat, Melbourne, held by Adam Bandt.
Election analyst Antony Green said the lack of a Liberal candidate played a crucial role in three previous ALP losses to the Greens in by-elections.
These included the federal seat of Cunningham in 2002, the West Australian state seat of Fremantle in 2009 and the Victorian state seat of Northcote in 2017.