Australians are evenly poised as Malcolm Turnbull commits Australia to a risky winter election on July 2, asking voters to back his plan for lower business taxes to fuel growth over Bill Shorten's alternative of higher taxes on the rich and business to fund vast new spending on hospitals and schools.

The government goes into the campaign proper, level pegging with an opposition that as recently as a few months ago was not even in the hunt.

With a wafer-thin lead of 51-49 in the latest Fairfax-Ipsos poll - or 50-50 if voter preferences are taken into account - the result cannot be predicted.

Mr Turnbull said the economic policy differences meant voters faced a decision that "cannot be clearer" whereas Mr Shorten called it an election about who voters trusted to protect services for ordinary people.

The Prime Minister's winter gamble comes as voters mark down his politically crucial budget as unfair 43 per cent to 37, and as polls confirm the opposition is on the rise, putting the eventual result on a knife-edge. Forty-six per cent of respondents said they were dissatisfied by the budget.

However a clear majority of voters at 53 per cent, still expect the Turnbull government to survive the longest campaign since 1966.

"At this election, Australians will have a very clear choice - to keep the course, maintain the commitment to our national economic plan for growth and jobs, or go back to Labor, with its high-taxing, higher spending, debt and deficit agenda," Mr Turnbull said, just minutes after visiting the Governor-General Sir Peter Cosgrove to have both houses of parliament dissolved.

Mr Shorten, speaking from Tasmania, said he was the one with the positive plan and that voters would opt for that over "three more years of dysfunction, of dithering and of disappointment".

"I will fight this election on schools and education ... I will fight this election to make Australia a fairer place, where the needs of families, small businesses, the great bulk of Australians, are placed at the top of the priority list," he said.

With Mr Shorten gaining ground as his personal standing improves, the do-or-die election will pit the two untried campaigners against each other in a presidential-style war of attrition likely to see strong negative attacks and its share of outright errors.

Mr Turnbull flagged more than one debate between himself and Mr Shorten, advising: "We haven't discussed debates but I look forward to having a number of them."

In an early sign of what many expect will be a campaign heavy on negativity, Mr Turnbull used his opening press conference to accuse Labor of planning to deliberately damage the economy, declaring "everything Labor is doing is absolutely calculated to stop our economic progress in its tracks".

"During this election campaign, my opponent, Mr Shorten, will ... continue to make very big promises of higher spending and I ask Australians when they hear these promises from him and from Labor to remember that Labor has no credible or coherent way to pay for them, other than through more debt and higher taxes," he said.

"We have an economic plan for growth and jobs ... on the other hand, our opponents are promising to increase income tax, they are opposing a tax cut for Australian businesses."

The election is expected to focus heavily on the leaders' personalities, but it will also be a contest between different philosophies, with the government banking on its 10-year $48 billion cuts in business taxes, designed to fire jobs and growth, and Labor opposing that outright emphasising instead heavy government investment in schools and hospitals.

The poll showed voters are evenly divided between the Coalition and Labor, with the former ahead by a whisker 51-49 when preference flows are modelled on the 2013 election.

However, when the 1410 respondents were asked for their second preference, in the national phone survey conducted from May 5-7, the two sides were locked together at 50-50.

That represents a 3.5 per cent swing away from the government and, subject to where the swings occur, could be enough to see a change of government in July.

Mr Turnbull remains strongly favoured by voters in the head-to-head contest, leading Bill Shorten as preferred prime minister 51-29.

But on the separate index of whether voters approve of the way each of the men are doing their jobs, Mr Turnbull is going backwards against a rising Opposition Leader.

Mr Shorten's approval rating has jumped by 5 points since April to be 38 per cent and his disapproval rating has also improved, losing 6 points in that time to be 49 per cent. That gives him a rating that is still in negative territory at minus-11.

Mr Turnbull is in a far superior position, with a positive overall rating of plus-8. However, this represents a sharp fall from his stratospheric approval rating of plus-51 shortly after assuming the leadership in October, 2015. His approval rating is down 3 points since April to 48 ad his disapproval has climbed by 2 to be 40 per cent.

Most concerning for the government is that just 37 per cent of voters say the budget last week was fair and fractionally more at 39 per cent described themselves as satisfied. That is substantially lower than the Coalition's primary vote, which came in at 44 - up 2 per cent on the April result, meaning not even all Coalition voters are happy with the budget.

Labor's anaemic primary support is the opposition's most persistent worry as it languishes at a meagre 33 per cent, which is 7 points lower than its peak in January last year, and equal with the level secured by Labor in 2013 when it lost to Tony Abbott in a landslide.

After redistributions in some states, Labor starts with a notional 57 seats, requiring 19 more to to reach a majority. The Coalition can afford to lose no more than 15 before it is unable to form a majority in its own right.

Follow us on Twitter