The major parties are neck and neck in the Sydney seat of Wentworth, and voters in the electorate are concerned that the new prime minister, Scott Morrison, is not as committed to action on climate change as Malcolm Turnbull was, according to a new opinion poll.

With Turnbull’s resignation about to trigger a byelection in the Sydney seat the former prime minister holds with a margin of 17.7%, the new ReachTel poll funded by the Australia Institute, with a sample size of 886 residents, suggests voters in Wentworth are focused on Morrison’s early steps on climate and energy.

While single-seat polls can be unreliable, the new survey suggests Wentworth voters are in a mood to punish the Liberals after the leadership civil war deposed their popular sitting member, with Labor polling 20%, the Greens 15% and interest in independent candidates in double digits in a poll taken on Monday night.

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The disaffection evident in the ReachTel poll echoes antagonistic voter sentiment in two reliable national surveys, the Newspoll and the Guardian Essential survey. Both have picked up a significant anti-Coalition swing in the wake of the leadership debacle – a different voter reaction to previous leadership coups, which delivered the government of the day a bounce.

Three Liberals have signalled interest in running in Wentworth: the former Business Council of Australia executive director Andrew Bragg, who quit his job on Tuesday night; a former Australian ambassador to Israel, Dave Sharma; and the City of Sydney councillor Christine Forster. The ReachTel poll suggests Sharma is polling 34.6%.

Undecided voters are almost as inclined to vote for an independent in the looming contest as for a Liberal candidate. The poll found that 36.5% of undecided voters leaned towards supporting a Liberal, while 32.7% said an independent.

While Morrison is under internal pressure from some quarters in the government to dump the national energy guarantee, withdraw from the Paris agreement and pursue coal-friendly policies, the ReachTel poll suggests this would be a risky position to adopt if the Liberal party wants to hold urban seats like Wentworth.

A majority in the sample, 66.6%, believes the Neg should include an emissions reduction target, which remains a major flashpoint within the Coalition. Almost 60% of the sample thought the Paris target of a 26% to 28% reduction in emissions should be increased.

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A larger group, 68.6%, said Morrison would do less to tackle climate change than the prime minister he replaced. Only 10% thought he would do more. Just over half the sample, 50.9%, said they would be less likely to vote Liberal after Morrison brought a lump of coal into question time in February 2017.

The risks of Morrison abandoning climate action extend beyond Wentworth. One of the lower house crossbenchers, Rebekha Sharkie, told Guardian Australia that if the new prime minister “decides to go down the pathway of an energy policy without an emissions reduction component, that is all but withdrawing us from Paris – and that would not sit well with my community at all”.

If the voter backlash ends up costing the Liberals Wentworth, Morrison will lose his one-seat majority in the House of Representatives, which will make the disposition of crossbenchers critically important.

Sharkie said she had spoken to Morrison on Saturday and he had pledged to stand by the government’s commitments to Mayo, made during the byelection when she defeated the Liberal Georgina Downer. She has reserved her position on confidence and supply, and lists the fate of the company tax cuts and the emissions reduction component of the Neg as issues of concern.

Senior figures have pushed back against abandoning the Paris treaty, and Morrison has appointed moderates to the portfolios of foreign affairs and trade. The retiring foreign minister Julie Bishop told reporters that Australia needed to stay the course: “When we sign a treaty, partners should be able to rely upon us.”

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She said: “I was part of the party room of August 2015 that unanimously endorsed the targets for the Paris agreement. I believe that Australia has a very high standing as a nation that keeps its commitments, and is part of the overall global effort for better outcomes for the world.”

The resources minister, Matt Canavan – who is pro-coal – said a withdrawal from Paris would hurt Australia’s international reputation.

Morrison’s new ministry was sworn in on Tuesday, and the prime minister’s immediate priorities are drought relief, settling the long-running schools funding row and dealing with high power prices.

The Neg is officially on ice. The new prime minister’s decision to split the energy and environment portfolios during his weekend reshuffle suggests it will remain there.

The prime minister said after the swearing-in ceremony on Wednesday that the immediate priority was power price reductions. He was noncommittal on the fate of the Neg. “There will be continuity in our policy in this area, but there will also be new ideas in this area, to ensure that we get those prices down.”