If the July 2 election repeats history that dates back to 1972, then what happens in five marginal seats in NSW and Queensland will provide the best pointer to the national outcome.
Top of the list is the NSW regional seat of Eden-Monaro that has been held by the government of the day since Gough Whitlam won power for Labor in 1972.
Junior minister Peter Hendy, who played an instrumental role in Malcolm Turnbull becoming prime minister eight months ago, won the seat in 2013 from Labor's Mike Kelly.
The pair is going head-to-head again in 2016.
Mr Hendy gets a head start this time around following a redistribution of NSW electoral boundaries.
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His 2013 margin has been extended from 1.2 per cent to 2.6 per cent with the addition of more Liberal-leaning rural booths.
Petrie in Brisbane's northeastern suburbs has been won by the election winners since 1987.
It's the coalition's most marginal seat in parliament, having been won Luke Howarth in 2013.
The outer western Sydney seat of Lindsay has been a government seat since its creation in 1984.
It changed hands in 1996 (Liberal); 2007 (Labor) and 2103 (Liberal).
Page on the NSW north coast also has a record of changing with government.
The Central Coast seat of Robertson has a long record of being held by a government MP.
For only a brief period has this original Federation seat been held by the opposition of the day.
Since 1983 it has always been held by the government.
