Labor and Greens voters regard the environment as their number one concern, whereas Coalition voters nominate the economy as the single most important issue to them, according to the first results from the ABC's Vote Compass survey.

Key points: The environment and the economy are the top issues for Australian voters

The environment and the economy are the top issues for Australian voters Health and super are next on the list

Health and super are next on the list The environment is the number one issue for those yet to decide how to vote

For One Nation voters, immigration is the most important issue.

The environment is rated as the number one issue by 29 per cent of Vote Compass respondents, a massive shift from just 9 per cent in 2016.

It is closely followed by the economy, which includes government spending and taxation, on 23 per cent.

Health care and superannuation, each on 8 per cent, are next.

Crucially, the environment is nominated as the top concern among undecided voters — 30 per cent of them say it is the most important issue, as opposed to 19 per cent who nominate the economy.

The Vote Compass survey is based on a nationally representative sample of 119,516 respondents.

Andrea Carson, a political scientist from La Trobe University and a member of the Vote Compass academic panel, said the environment was a potential "wedge issue" for the Coalition.

"Even though overall [Coalition] voters don't tend to nominate the environment as their most important issue, the Coalition — in order to win seats — need some of those undecided voters.

"They are going to have to be very careful how they message around the environment."

But the economy remains top concern for many

The difference in what matters most to voters of different stripes is stark:

For Labor voters, the environment was the top issue (40 per cent), followed by the economy and health care (each 11 per cent).

For voters, the was the top issue (40 per cent), followed by the and (each 11 per cent). For Coalition voters, the economy was the top issue (44 per cent), followed by the environment and superannuation ( each 10 per cent).

For voters, the economy was the top issue (44 per cent), followed by the and each 10 per cent). Among Greens voters, not surprisingly, the environment was overwhelmingly the major issue (63 per cent).

Among voters, not surprisingly, the was overwhelmingly the major issue (63 per cent). And One Nation voters were most concerned about immigration and refugees (32 per cent), followed by the economy (16 per cent).

ABC election analyst Antony Green said it was "surprising" that the issue of the environment was showing up as more of a concern than health and education among Labor voters, but that the party's focus on the latter issues might be designed to attract uncommitted voters, such as older voters and younger voters with children.

"So the focus may be more on those issues because it may shift people's votes, where on the environment Labor has already got those people locked on."

Millennials are most concerned about the environment

Age is a big factor in what voters care about, too, with 39 per cent of respondents aged under 35 nominating the environment as their greatest concern.

Immigration and refugees came in as the third-biggest issue for young people.

The environment and the economy were of roughly equal concern to those aged 34 and up, with the middle cohort of those aged 35 to 54 more concerned about unemployment than over 55s, who nominated superannuation as their third-biggest issue.

At least 30 per cent of voters regarded the environment as the most important issue regardless of their education level, from high school through to Bachelor degree level.

Geography is a factor too

The environment was the most important issue for voters in the southern states and territories — NSW, Victoria, South Australia, Tasmania and the ACT.

Voters in the commodity rich states of Western Australia and Queensland, along with the Northern Territory, were more concerned about the economy.

In Tasmania, health care was nominated as the top issue by 16 per cent of voters, substantially higher than in any other state.

LGBTQI issues, which included the same-sex marriage debate in 2016, were rated less important this time around compared with the last election.

About the data