The starting gun's been fired for five federal by-elections, with Labor staring down the barrel of two potential seat losses.
Parliamentary Speaker Tony Smith issued the writs on Friday for by-elections to be held in the seats of Perth and Fremantle (WA), Braddon (Tasmania), Mayo (SA) and Longman (Queensland) on July 28.
Four of the by-elections were triggered by MPs facing dual citizenship questions, while Labor's Tim Hammond retired in the seat of Perth for family reasons.
Former Nick Xenophon Team representative Rebekha Sharkie will recontest her seat of Mayo for the Centre Alliance, but faces a tough challenge from the Liberals' Georgina Downer, the daughter of former Howard government minister Alexander Downer.
Labor won't face Liberal contestants in Perth and Fremantle.
However, the Liberals are in with a shot to unseat Susan Lamb in Longman and Justine Keay in Braddon.
In both seats, the Liberal campaign machine is targeting Labor leader Bill Shorten's personal unpopularity with voters and the fact that the federal opposition acted so slowly against its MPs who had citizenship doubts.
Former federal Liberal MP Brett Whiteley is running in Braddon, while ex-state MP Trevor Ruthenberg is making a tilt for Longman.
However, Labor has been campaigning heavily on its personal income tax cuts plan, higher spending on health and education and stemming the impact of penalty rate cuts which take effect on July 1.
History also favours Labor, as federal by-elections tend to swing against the government by a factor of about four per cent and only five of 151 by-elections had resulted in opposition seats being lost.
Electoral rolls will close on June 22.
Nominations will close on July 5 with the declaration of nominations a day later.