Western Australia would ban foreign donations and introduce spending caps for election campaigns under new laws introduced to parliament.
But the Liberal opposition has accused the government of targeting billionaire mining magnate Clive Palmer, and signalled it won't support the proposed legislation unless it is tweaked to also include caps on union spending.
The proposed changes would make it unlawful for political parties and associated entities to accept money unless the donor is an Australian resident or citizen or has an ABN.
Donations and gifts would be reported quarterly, rather than annually, and the threshold for disclosure reduced from $2500 to $1000.
Spending will also be capped at next year's state election, with parties and independent candidates limited to $125,000 on each district or region they contest.
Any overspends would need to be balanced by a reduction in other districts, while entities that are not political parties, candidates, or legislative council groups would be capped at $2 million.
Opposition Leader Liza Harvey has cast doubt on the government winning support for the legislation, which was introduced to parliament on Thursday.
"If you have a look at the last election in this state, the unions spent more collectively than either of the political parties, so if there are changes to the Electoral Act that don't include caps on union spend during the campaign, I doubt it will have the support in the Legislative Council," Ms Harvey said.
"I have no doubt this legislation is targeted at Clive Palmer. You have to have a fair playing field. You can't just single out one individual and one party. It has to be fair for everyone."
Mr Palmer, a noted critic of WA Premier Mark McGowan, has not ruled out running candidates at next year's state election.
The Queenslander donated more than $80 million to his own United Australia Party in his failed bid for federal parliament last year.
Electoral Affairs Minister Stephen Dawson said the reforms weren't about Mr Palmer and had been planned since 2016.
"This is not about individuals, nor indeed groups" he told reporters.