Next week's election in Australia is shaping up to be one of its tightest in history.
Most opinion polls indicate the possibility of a hung parliament.
But a Roy Morgan poll released on Thursday night bucks the trend and gives Labor a decisive lead.
The Morgan poll has Labor on a lead of 57.5% compared to 42.5% for the Coalition on a two-party basis.
Labor's primary vote is up five points to 43% ahead of the Liberals on 37%.
Radio New Zealand's political editor says it is very likely the Green Party will hold the balance of power in the Senate.
The Greens currently have five members in the Senate.
The contest between Prime Minister Julia Gillard and Liberal Party leader Tony Abbott has shifted from Queensland to West Sydney, where Labor is anxious to hang on to a number of marginal seats.
Labor is particularly worried it might lose Bennelong, the seat it won off former prime minister John Howard at the last election.
Voting day is 21 August.