The leader of Australia's conservative Liberal Party-led coalition prompted the election by dissolving both houses of parliament in May, blaming intransigent independents in the upper house Senate for blocking his agenda.
He has also cited the economic uncertainty caused by UK's decision to leave the European Union as another reason to vote for a stable government.
The latest Newspoll in News Corp Australia publications placed the Coalition just ahead at 50.5 percent to Labor's 49.5 percent in two-party preferred terms.
Labor leader Bill Shorten has spent early Friday in Sydney's western suburbs, where its millions of residents could sway an election result.
He has campaigned on a platform focussed on education and health policies.
"The cuts are severe and they are real," he told reporters on Saturday morning, referring to the Coalition's health policies.
Turnbull has argued that minor parties, possibly in a coalition with centre-left Labor, could not be trusted to manage an economy hampered by the first mining downturn in a century and balance public finances after years of deficits.
Turnbull's coalition is facing a strong challenge from Labor, as well as from independents and minor parties like the Greens which could win enough seats to hold the balance of power in the Senate or force a minority government in the lower house.
The centrist Independent South Australian Senator Nick Xenophon, whose party is fielding almost 50 candidates across the country, is expected to emerge with considerable influence.
"These are in the national interests, to deal with issues of manufacturing," Xenophon told reports in his home state, which represents one of the country's weakest state economies.
"We are facing a tsunami of job losses by the end of next year when auto-making shuts down in the country."
Far-right parties, including Pauline Hanson's One Nation, have campaigned on anti-immigration, anti-Muslim agendas. Hanson is a strong contender to win a position in the Senate.
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