Gareth Morgan's Opportunities Party (TOP) is offering free shuttle bus rides to Mt Albert voters, but Newshub can reveal it's landed them with an official complaint.
Geoff Simmons is standing for TOP in the upcoming Mt Albert by-election, and ACT leader David Seymour says the shuttle service is a blatant attempt to win votes.
"The most pernicious part of it is you have to prove you're a Mt Albert voter before he can offer it to you," Mr Seymour told Newshub.
A photo on The Opportunities Party's official Facebook page promotes the service for a lift to the cricket this Friday, along with a registration link.
Small print in the registration form reveals "we can only pick up those within the Mt Albert electorate".
Mr Seymour believes it's a breach of the Electoral Act and has lodged an official complaint with the Electoral Commission.
"If he was doing it for everybody you might say 'he's being generous, good on him,' but the fact it's only for voters in the by-election where he's running a candidate shows it's a blatant breach of the law."
Mr Seymour says the shuttle rides are enough to be considered treating, a practice that breaches the Electoral Act of 1993.
"I've seen people break the electoral law accidentally but this is so blatant I think it should be referred to the police."
It won't be enough to stand Mr Simmons down as a candidate, but if the Electoral Commission refers the matter to police then charges could be laid.
Mr Simmons says all the fuss shows his opponents are scared.
"Someone must really be worried about our potential in this by-election if they're disturbed about giving people free rides to their cars on a hot muggy day," he said.
"No flyers, no sell about voting, so yeah, we're pretty secure on the treating rules."