Labor vowed before the election to ban all political campaign donations from individuals, businesses and unions, with political parties potentially moving solely to a public funding model.

It’s the first move of its sort in SA since former Liberal leader Isobel Redmond sought to crack down on big donations to political parties – a push that ultimately failed to materialise.

Attorney-General Kyam Maher said work on how to best implement the “blanket ban” was currently underway.

“Almost immediately after we won office, we had the Attorney-General’s Department and the best legal advisers in South Australia giving us views about how we can implement the banning of political donations,” Maher told reporters on Tuesday.

“Other states have done this in some form – Queensland and New South Wales ban classes of donors – so we’re looking at work that’s previously been done.

“There are constitutional issues we need to look at when we do the drafting to make sure we overcome.”

Before the election, Labor indicated it would be seeking advice from the Solicitor General about potential legal challenges to the donations ban.

Political donation caps in New South Wales have faced challenges in the High Court on the basis of infringing on implied constitutional rights to freedom of political communication.

Asked whether the legislation would be before parliament this year, Maher said: “I’m not sure we’ll get it in this calendar year but certainly in place before the next election.”

“Well and truly before the next election, so all parties know what the rules are and have this applying to them,” he said.

“It is something that as a Labor Government we feel very strongly about … that election campaigns are a contest of ideas, not a contest of money.

“I think we all think that’s very very important, that’s why we’re making sure we get this legislation right.

“We will in time for the next election have this policy in place.”

Labor has previously flagged it will seek Liberal and minor party support for its political donations ban.

Premier Peter Malinauskas – a former state secretary of the Shop, Distributive and Allied Employees union, the power base of Labor’s Right faction in SA and a major financial backer of the ALP – said the donations ban “generally isn’t widely supported in some quarters”.

“There are certainly members of the Liberal Party that have got reservations around it, I know that there are business donors that don’t necessarily love it, I know that there are union donors that don’t necessarily love it,” he said.

“But I believe it to be the right thing to do.

“I was able to carry the day in terms of that argument or that debate internally about this policy. I’m very glad that I took it to the election.”

It comes after Labor’s state executive moved on Monday to return a controversial $125,000 election donation from the John Setka-led Victorian branch of the Construction, Forestry, Maritime, Mining and Energy Union’s (CFMEU) construction division.

The Opposition and Setka’s estranged wife Emma Walters – whom the polarising construction union boss was convicted of harassing in 2019 – called on Malinauskas to hand the $125,000 donation to a domestic violence charity.

Malinauskas, who had initially resisted calls to hand back the money, requested on Monday the state executive return the donation after allegations that cars belonging to the Master Builders Association were vandalised and had CFMEU-branded stickers placed on them.

“When people were asking me some weeks ago about my views about the [$125,000] donation and the news emerging that it came from the Victorian branch and the Victorian branch was amalgamating to the South Australian branch, I made it clear that I wouldn’t tolerate bad behaviour,” Malinauskas said on Tuesday.

“And If I saw evidence of that emerge I would act – and that’s exactly what I did upon becoming aware of what occurred last Friday.”

CFMEU SA branch secretary Andrew Sutherland said no allegations of vandalism had been put directly to the union, and he called on the premier to provide any proof that union officials or employees were involved.

“If the premier has evidence that would assist the CFMEU in investigating the matter, we ask that he provide it to us without further delay,” Sutherland said in a statement.

“The CFMEU does not, and has not, authorised, encouraged, or sanctioned any acts of vandalism.”

Sutherland said the $125,000 donation to Labor was made by the Victorian-Tasmanian branch on behalf of its 28,000 members and in cooperation with the SA division’s 2000 members.

He said it was not made personally by any official and was no different to donations made by any other union.

– with AAP