Only one in five voters expect Malcolm Turnbull to hold onto government at the next election, a new poll shows.
The latest Essential poll published on Tuesday puts Labor in a 54-46 two-party lead over the coalition.
Asked about their expectations, 20 per cent of voters said the coalition would win the next election, with 36 per cent rating Labor, 18 per cent believing it would result in a hung parliament and 26 per cent saying "don't know".
A third of voters say the prime minister should call an early election, but 47 per cent want the government to run its full term.
The poll comes as the coalition faces by-elections in the NSW seats of Bennelong and New England.
Mr Turnbull is seeking to turn around the coalition's prospects by flagging possible income tax cuts in the May 2018 budget, just three months ahead of the first opportunity to go to a lower house and half-Senate election.
However, it would not come at the cost of the promised budget surplus in 2020/21, on which the government's economic credentials depend.
"Our determination is to ensure that we have more dollars left in the pockets of hardworking Australians," Mr Turnbull told reporters in Sydney on Tuesday.
The prime minister is facing criticism over his postponement of a House of Representatives sitting next week, which he says is due to the Senate not likely to complete its debate on same-sex marriage in time for the lower house to consider it.
Labor leader Bill Shorten said Mr Turnbull was trying to hide from a banking commission of inquiry, which could be set up if a handful of coalition MPs cross the floor.
"Tradies, teachers and nurses don't get to cancel their day and pull the doona over their head. It's crazy," Mr Shorten told the Seven Network.
He said the tax cut was a "thought bubble" and would be eroded by the government's plan to hike the Medicare levy.
Labor frontbencher Anthony Albanese said if Mr Turnbull was not up to governing "he should just call an election".
