Labor remains ahead of the Coalition in the latest Guardian Essential poll, which suggests voters like social spending more than they like tax concessions, but points to mixed views on the medical evacuations bill.

The new survey, which puts Labor in front of the Coalition on the two-party-preferred measure 52% to 48%, comes as Scott Morrison will confirm on Tuesday his government will greenlight a commitment of up to $1.38bn for the long-mooted expansion of the Snowy Hydro scheme as part of the government’s attempted climate change pivot.

While Malcolm Turnbull had telegraphed spending of $2bn for his pet project, adding 2,000MW of new generation capacity, Morrison will pledge up to $1.38bn in an equity investment, with the remainder of the project to be financed by Snowy Hydro Limited. A feasibility study for the project in 2017 predicted the total cost could be up to $4.5bn.

“Snowy 2.0 will inject the energy supply and reliability of our electricity market needs, helping cut costs to families and businesses and cut Australia’s emissions,” Morrison said ahead of Tuesday’s announcement.

With the prime minister focusing on climate, Labor will press ahead on Tuesday with its rolling response to the Hayne royal commission into the banks, allocating $120m from its proposed banking “fairness” fund to boost the number of financial rights lawyers from 40 to 240 across Australia.

The new poll of 1,085 respondents puts the Coalition’s primary vote on 38% and Labor’s on 37%, with the Greens on 9%, Pauline Hanson’s One Nation on 6% and support for “others” and independents on 10%.

The latest two-party-preferred result, which is consistent with this week’s Newspoll, suggests a tightening in the political contest between the major parties.

The Guardian Essential survey a fortnight ago, which followed the final report of the banking royal commission, put Labor ahead of the government 55% to 45%. A month ago, the two-party-preferred result was the same as this fortnight.

With the Coalition sharpening its negative campaigning on Labor’s tax measures and on border protection as the election draws closer, voters were asked a number of questions about tax policy and about the medical evacuations bill passed during the parliamentary last sitting.

The largest group in the survey, 38%, said the medical evacuations bill struck the right balance between strong borders and humane treatment, while 15% said it did not go far enough to protect people in offshore detention, and 30% felt it would weaken Australia’s borders.

The sample split again over whether the passage of the bill would influence their vote at the coming election.

Just over a quarter of the group said it would, with this cohort predominantly “other” voters (36%), Liberal/National voters (32%) and men (30%). In this group, 57% were of the view that the new protocols weakened Australia’s borders, and 19% felt the procedures did not protect the wellbeing of people in offshore detention sufficiently.

Another chunk of the sample, 35%, reported the package would have a moderate influence at the election, including 18-34 year olds (47%), women (38%), and Greens voters (38%).

Thirty eight per cent said the issue would have no influence on their vote, with those most likely to say this being voters aged over 55 (44%), Labor voters (42%) and those aged 35-54 (40%).

On tax, over half of the sample (53%) were more likely to support closing off loopholes and concessions and directing the revenue towards funding for schools, hospitals and other social programs. That principle had majority support among men, women and most age groups except for people over 55, although support from this cohort remained at 48%.

A majority of the sample (68%) expressed a preference for investing in social and community housing over the preservation of negative gearing concessions (32%). A majority again (61%) nominated funding universal access to early learning for three- and four-year-olds over continuing tax credits for “people with shares who do not pay any income tax” (39%), and increasing the Newstart allowance was a more popular idea than continuing “to allow people to split incomes through family trusts to minimise tax”.

Asked which was the better party on tax policy, Labor was seen as best for first-homebuyers, pensioners and workers earning up to $150,000 per year, while the government was seen as the best party for property investors, people who use family trusts, self-funded retirees and workers earning more than $150,000 per year.

Morrison has branded Labor the party of higher taxes, but voters perceptions of that are mixed. Thirty-five per cent agrees Labor will increase taxes while 22% disagree and 43% are either neutral or don’t know, and 37% agree with a statement that taxes will always be higher under Labor while 23% disagree and 40% are either neutral or don’t know.

Voters were asked to rank the issues they felt the government should address over the next 12 months. Top of the list was improving the health system (31% of the sample placed it in their top three), reducing utility bills (31%) and creating jobs and reducing unemployment (28%).

A focus on the fate of refugees, and the imperative of combatting international crime and terrorism, was much further down the list of priorities. Six per cent put refugees and fighting terror in their top three issues.