The August 21 election will decide the fate of the government's planned 30 per cent mining tax on big iron ore and coal projects, and its plans for a $33bn national broadband network.
A separate Newspoll in the must-win states of Queensland and New South Wales (NSW), and Gillard's home state of Victoria, showed the prime minister was on track to scrape into government.
"Possible gains in Victoria would mean Labor could govern in its own right by the narrowest of margins," said The Australian newspaper, which published Newspoll.
Gillard performed strongly in the campaign's fourth week - the period during which the surveys were conducted.
By contrast, Abbott attracted widespread derision with a vow to scrap the government's National Broadband Network, and floundered over details of his own cheaper but slower internet scheme when quizzed on national television.
"Labor's in front and is likely to win, but government is still there for the taking for Tony Abbott"
The Australian newspaper based on Newspoll
The Nielsen poll found more people disapproved of Abbott's performance than approved (48 per cent to 45 per cent), giving him a net negative for the first time in the campaign.
Gillard's approval rating rose to 54 per cent and her disapproval dropped to 36 per cent.
The Newspoll of 3,351 voters in marginally-held seats showed a significant swing to Gillard in Victoria, countering considerable gains by Abbott in Queensland and New South Wales (NSW).
"Labor's in front and is likely to win, but government is still there for the taking for Tony Abbott," The Australian said.
Critically, Gillard looked to hold onto the bellwether electorate of Eden-Monaro, just outside the capital Canberra, according to Newspoll.
Every government which has won office since 1972 has taken the seat.