SUPER SATURDAY OF BY-ELECTIONS:
* Australia has never had five federal by-elections on the one day, with federal Speaker Tony Smith setting the date for July 28.
* Voter rolls close on June 22, while nominations close on July 5.
THE SEATS AND CANDIDATES SO FAR:
* LONGMAN - Queensland seat held by Labor's Susan Lamb with margin of 0.8 per cent.
Lamb's dual British citizenship triggered the by-election, but she will recontest. The Liberal National Party, standing former state MP Trevor Ruthenberg, will be the largest beneficiary of One Nation preferences. Labor will need a strong primary vote and Greens preferences to hold the seat.
* BRADDON - Tasmanian seat held by Labor's Justine Keay on 2.2 per cent margin.
Keay was also a victim of the dual citizenship saga, acquiring British citizenship through her father. She will recontest. Former independent senator Jacqui Lambie has ruled out a tilt. Liberals believe former MP Brett Whiteley can win it back, having lost it in 2016.
* FREMANTLE - WA seat held by Labor's Josh Wilson on a 7.5 per cent margin.
Another victim of the citizenship saga. He will recontest. Wilson has a healthy margin in the seat of former Labor prime minister John Curtin. The Greens will contest, but are unlikely to succeed. The Liberals won't stand a candidate.
* MAYO - South Australian seat of Centre Alliance (formerly Nick Xenophon Team) Rebekha Sharkie, held by 5 per cent.
Sharkie's British dual citizenship led to the by-election. She will recontest but with the new party brand Centre Alliance, not the Xenophon name. The Liberal Party wants its seat back and have chosen Georgina Downer, daughter of former federal minister Alexander Downer.
* PERTH - WA seat held by Labor's Tim Hammond on a 3.3 per cent margin.
Hammond is retiring to spend more time with his family. Labor has preselected its state secretary Patrick Gorman, a former Kevin Rudd staffer and mastermind of Labor's 2017 WA state election victory. The Liberals are not contesting it, which has angered party members. Labor is likely to hold the seat.