PM Scott Morrison says he has united his conservative government in the nine months since he replaced Malcolm Turnbull.
Labor opposition leader Bill Shorten has pressed his case with stark policy alternatives.
Australia has mandatory voting and a record 16.4 million enrolled voters.
The nation holds elections every three years, but no prime minister has succeeded in serving a full term since 2007.
The poll takes place just two days after the death of Bob Hawke, a long-serving former prime minister whose achievements have been hailed across the political spectrum.