An analysis of recent opinion polls suggests the chances are growing for a hung parliament following the August 21 poll.
The Reuters Poll Trend, which uses data from from Morgan, Newspoll and Nielsen to create a fortnightly average, shows support for Prime Minister Julia Gillard and her Labor government has slumped.
The poll trend found support for Labor had dropped 2.5 percentage points to 51.5 per cent since campaigning started.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
If the trend was uniform across the country and continued to polling day, Labor would have trouble holding onto power.
"Gillard would scrape back into office with a reduced majority, although she could be forced to deal with independents to hold onto power," Reuters said in statement.
Australia last had a hung federal parliament in 1940, when Robert Menzies's United Australia Party and the Country Party clung to power, with the support of independents.
In 1941, the government, then headed by Arthur Fadden, was unable to retain majority support in the lower house, paving the way for Labor's John Curtin to become prime minister.
The 2008 state election in Western Australia also resulted in a hung parliament, where the Liberals formed government with the support of The Nationals and three independents to oust Labor.
Ms Gillard continues to outpoll Mr Abbott by 13.3 points as preferred prime minister in the the Reuters Poll Trend.
But her popularity has slumped 11 points in the past two weeks.
