Early federal election options - a primer

AN EARLY FEDERAL POLL? LET'S LOOK AT THE OPTIONS.

POSSIBLE DATES:

* First possible date for a normal house of representatives and half-senate election is Saturday August 6; the last January 14, 2017.

* House-only election could be held before August 2016, but a half-senate election would be needed by May 13, 2017.

* Last opportunity to call a double-dissolution election for the House and all of the Senate is May 11, the day after the budget.

* Most likely date for a double-dissolution election is July 2, following a seven-week-plus campaign.

PREVIOUS DOUBLE-DISSOLUTION ELECTIONS:

* Joseph Cook called one in 1914, and won five seats.

Robert Menzies 1951, lost five seats.

* Gough Whitlam 1974, lost one seat.

* Malcolm Fraser 1983, lost government.

* Bob Hawke 1984, retained government with a reduced majority in a bigger parliament.

* Hawke again in 1987, won four seats.

THE CASE FOR A DOUBLE-DISSOLUTION ELECTION:

* Clears the decks of recalcitrant crossbench senators. Under planned changes to the way Australians vote for the senate, crossbench numbers are likely to fall from eight now to two or three - possibly all from the Nick Xenophon group.

* The coalition is likely to win half the seats in the senate, with Labor, Greens and Xenophon group sharing the other half.

THE CASE AGAINST:

* Lack of plausible triggers. So far only two pieces of government legislation - abolition of the Clean Energy Finance Corporation and new governance rules for trade unions - have been rejected twice by the senate.

* The related mechanics. The post-budget day deadline; requiring parliament to fast-track money bills; a long and arduous election campaign with the potential to antagonise voters.

WHAT THE GOVERNMENT IS CONSIDERING:

* Bringing the budget forward to May 3 and use the sitting days until May 11 to have parliament approve its money bills and forcing the senate's hand on legislation to restore the building industry watchdog. A second rejection would give it a legitimate trigger for a double-dissolution election and provide a key plank for its re-election campaign.