It was the sleeper issue that ended up dominating the Queensland election campaign – and, in the end, activists believed, may have saved government for Labor.

Labor sits the closest to the majority needed to take government in Queensland, 47 seats, after receiving gains in the south-east, largely helped by a drop in support for the Liberal National party.

Among those were Maiwar, the electorate held by the shadow treasurer, Scott Emerson, who looks to have lost largely due to Greens preferences, along with other LNP-held inner-city seats such as Mount Ommaney and Mansfield, which both look to have fallen to Labor.

Exit polls commissioned by GetUp in those electorates found up to 70% of respondents were against the billion-dollar rail line loan for Adani, while another 30% said Labor’s decision to veto the loan helped decide how they would vote.

“We already know the majority of voters from every single party at play opposed the Naif loan, including LNP and One Nation voters,” the GetUp environmental justice director, Sam Regester, told Guardian Australia. “Taking a stronger position against Adani clearly contributed to the swing in south-east Queensland. Just as tellingly, Labor held on to the regional seats that folks like conservative analysts predicted would fall because of the veto.”

As of Sunday evening, the rural Labor seat of Mirani looked like falling to One Nation, while Townsville, which had been considered to have been saved for Labor, was slipping back to the LNP on postal and pre-votes.

Both were areas where voters support the Adani mine but, on Sunday, Labor strategists were putting the probable losses down to support for One Nation.

“I don’t think the Adani veto was a big deal to our campaign because, if it was, I think it would have shown up in Thuringowa [in north Queensland]. For us, it was an issue which distracted our campaign from day one and it meant we got no clear air, we were asked about it every single day.

“Then the veto happened and we were still asked about it, because it was the most interesting thing happening. Then Pauline Hanson entered the campaign and she became the most interesting issue.

“I think it stopped us from being able to talk about our issues at first and then, with the veto, we eventually managed to move on.”

Regester said that was because voters in the south-east, particularly, saw a point of difference.

“The strong showing of the Greens, particularly in south Brisbane and Maiwar, showed more than anything the value of having the clearest, strongest policy on Adani,” he said. “ For most of the last term of government, the two major parties were equally bad on this key issue, so it’s no wonder they picked up a swag of votes.

“Labor was able to offset this somewhat with the Naif veto but this election made it clear that the Greens can be a threat to both major parties when they’re not up to scratch, particularly on Adani.”

Galaxy’s exit poll, based on 1760 voters across 18 electorates across Queensland, had jobs, health and stable government as the top issues for most voters, with the Adani mining development being named as the most important issue by just 16 per cent of voters.

Other campaigners weren’t quite so sure the veto issue could be dismissed.

“I think it is hard to say,” another Labor strategist said. “It was certainly a dominant issue during the campaign. It was always a feature of internal party polls – with mixed results.”

Those mixed results came from a south-east vote, which was either pleased, or apathetic, about the loan veto, contrasting with a desire in central and north Queensland to see the mine begin work as soon as possible.

The veto proved an issue against Labor in Rockhampton, where the independent candidate, former mayor Margaret Strelow, who failed in her bid for Labor preselection despite Annastacia Palaszczuk’s support, strongly spoke out against the decision to bypass the loan.

Strelow’s preferences are now looking instrumental in deciding the seat. In Townsville, the mayor, Jenny Hill, a known friend of Palaszczuk, was also critical of the decision and did not appear with Labor during Palaszczuk’s campaign visits. Townsville is another seat going down to the wire for the incumbent government.

But some within the LNP, who are facing what has become known as “teal” seats, particularly in the inner-suburbs of cities, where voters may be socially conscious but economically conservative, believe the veto was enough to drive votes to the Greens.

It was those preferences that look like handing seats to Labor.

“It was a significant emotional issue for Greens voters which motivated them,” one LNP strategist said in the washup. “In my view, the loan is dead.”

Others were a little more pragmatic.

“Do I think anyone wants to see a billion of taxpayer dollars go to a mining company? No, I don’t think anyone is overly in support of that,” an LNP campaigner said. “But what could we do? It’s not like we could veto something our own federal government set up.”

Palaszczuk announced she would veto the loan at the end of her first week of campaigning. Up until then, she was followed by anti-Adani protesters, who ambushed her at events, with the gatecrashing dominating the news cycle.

Announcing that she had learned of a “smear campaign” by political opponents, to reveal her partner’s role at PriceWaterhouseCoopers in helping Adani put together its loan application for the rail line, presenting a conflict of interest, Palaszczuk said if she won government, she would veto the loan.

Under the Naif rules, the states need to give approval for the loan. On Sunday, Palaszczuk confirmed she would stand by the veto decision. She also committed Labor to not allowing any taxpayer funds to flow to the mine, or its associated infrastructure, although has refused to give details of the royalty holiday granted to Adani, worth about $350m, which she said would be paid back with interest.

“We will veto the loan, they said on the 6th of June that they had the green light that they would build the mine and the rail line and we expect them to get on with it,” a Palaszczuk spokesman said.

The future of Adani now rests on whether it can receive financing to begin construction in the Galilee Basin, with some reports it may be close to securing Chinese money to open the mine. That has the potential to create another issue for the Queensland government, be it the LNP or Labor, as both have said they remain in support of the mine for the jobs it will create, with the Chinese funds potentially coming with Chinese labourer and steel strings attached.

GetUp have not finished fighting the project and Regester said Labor’s position was “still nowhere good enough” and a potential issue for the next federal election.

“After watching Adani dominate the state election, there will be folks in federal Labor keen to not see the next federal election nearly derailed in the same way,” Regester said. “It’s in their interest to get on the right side of this extraordinary movement and oppose the entire Adani [mine] outright.”