Super Saturday: Snapshots of the five electorates voting

Here is a snapshot of the five electorates holding by-elections.

* Longman is just north of Brisbane, with major centres including Caboolture.

* By-election triggered by May resignation of Labor's Susan Lamb over her dual British citizenship.

* Held by Lamb with a 0.8 per cent margin.

* Lamb is standing again but faces a tough challenge from Liberal National Party candidate Trevor 'Big Trev' Ruthenberg.

* Ruthenberg's campaign was de-railed over his misrepresentation of a military medal, for which he apologised.

* Preferences from One Nation's Matthew Stephen will be crucial.

* Expecting strong vote for minor parties and independents.

* 11 candidates have nominated.

* Key issues: health, penalty rates, jobs.

Trevor Ruthenberg, One Nation's Matthew Stephen and Labor's Susan Lamb are fighting to win Longman. Source: AAP

* Mayo takes in the Adelaide Hills through to Kangaroo Island.

* By-election triggered by May resignation of Centre Alliance's Rebekha Sharkie over her dual British citizenship.

* Held by Sharkie with a five per cent margin.

* Sharkie is expected to retain the seat but faces a challenge from the Liberals' Georgina Downer, the daughter of former federal minister Alexander Downer.

* If elected Downer will be the fourth generation of her family to serve in federal parliament.

* Seven candidates have nominated, including Labor's Reg Coutts.

* GetUp has run a public campaign linking Downer to cuts to the ABC. The Liberals have countered saying voting for Sharkie is the same as voting for Labor.

* Key issues: health, ABC funding, education.

Centre Alliance candidate Rebekha Sharkie (l) is expected to win back Mayo on Super Saturday. Source: AAP

* Braddon is situated in northwestern Tasmania, with major centres including Devonport and Burnie.

* By-election triggered by the resignation of Labor's Justine Keay over her dual British citizenship.

* Held by Keay with a 2.2 per cent margin.

* Keay is behind in the polls and betting markets, with former Liberal MP Brett Whiteley on track for a narrow win.

* Eight candidates have nominated.

* Bill Shorten and Malcolm Turnbull have campaigned heavily in the seat.

* Key issues: health, job creation, fishing.

Brett Whiteley, with Prime Minister Malcolm Turnbull, is in with a chance of winning Braddon. Source: AAP

* Perth is based on the central part of the West Australian capital.

* By-election triggered by May resignation of Labor's Tim Hammond who retired so that he could spend more time with his young family.

* Held by Hammond with a 3.3 per cent margin.

* Labor candidate Patrick Gorman, former Kevin Rudd staffer and WA Labor secretary, is expected to win.

* Fifteen candidates have nominated, but no Liberal candidate standing

* Key issues: education, transport, health, WA's GST share.

Former Kevin Rudd staffer Patrick Gorman. Source: AAP

* Fremantle is centred on the city, south of Perth.

* By-election triggered by May resignation of Labor's Josh Wilson over his dual British citizenship.

* Held by Wilson with a 7.5 per cent margin.

* Wilson is expected to win, with no Liberal candidate contesting the by-election.

* Seven candidates nominated.

* Key issues: roads, health, WA's GST share.

Labor candidate for Fremantle Josh Wilson. Source: AAP

Follow live coverage of Super Saturday on the SBS News website and the SBS News app on iOS and Android.