The nine-week campaign surpasses the disastrous eight-week general election campaign Malcolm Turnbull called in 2016 and vindicates Labor suspicions the government would try to stretch the date so as to cruel the national conference, an event held once every term of Parliament and which is the premier policy event and pre-election launch pad.

This year's event will be held in Adelaide. Already the convention centre and thousands of hotel rooms and flights have been booked.

Labor Senate leader Penny Wong used a Senate estimates hearing to question the independence of electoral commissioner Tom Rogers and allege Mr Smith was leant on by the government which appoints him.

Mr Rogers contended it was not his role to set the date of byelections but provide advice. The Speaker made the ultimate decision.

The Speaker made the ultimate decision. Labor is outraged. Dominic Lorrimer

Labor is outraged, pointing out voters in the five seats would wait 79 days to elect their new MPs and wouldn't have new representatives in Parliament until at least August 13. Ths is the fourth longest byelection campaign of the 16 held since 2000.

Deputy Labor leader Tanya Plibersek indicated Labor would have to shift its conference date and said the move was "a disgraceful delay and a sneaky tactic from Malcolm Turnbull".

"It would appear this has been deliberately designed to disadvantage the Labor Party, given our national conference is scheduled for that weekend.


"This will obviously have implications for our national conference. Our activists will want to be out in the community campaigning for Labor, not sitting in a conference centre.

"Malcolm Turnbull owes the Australian people a serious explanation for this unacceptably long wait."

Labor's manager of opposition business Tony Burke said the delay was unnecessary, given a full federal election could be called in 33 days.

Byelections will be held in the seats of Perth, Fremantle, Braddon, Longman and Mayo.

The new candidate nomination forms prepared for the government to avoid a repeat of the dual citizenship saga include information about candidates' parents and grandparents born outside of Australia, spouses born outside Australia and whether the candidate has taken any steps to assure themselves they "have not acquired citizenship of another country by descent, marriage or other means".