Due to the High Court ruling against Senator Katy Gallagher on 9 May 2018 as part of the ongoing parliamentary eligibility crisis, Sharkie and three other MPs in the same situation announced their parliamentary resignations later that day,[1] while the Perth incumbent resigned for family reasons.

Popularly labelled "Super Saturday", the occurrence of five simultaneous federal by-elections is unprecedented in Australian political history.

[4] The others are: Liberal candidate Georgina Downer deleted her Twitter account on 13 June 2018, claiming that trolls had been attacking her with bad language, with counterclaims from Twitter users that she had deleted legitimate policy questions posted to her Facebook account.

[5] Historically, the rural seat of Mayo has been a comfortably safe Liberal seat in two-party terms, though over the past two decades, the Liberals in Mayo had been repeatedly left vulnerable by several strong election results from minor parties and independents.

[7][8][9] Key dates in relation to the by-election are:[10] Candidates are listed in the order they appeared on the ballot.