Legal experts say a leaked recording of Simon Bridges doesn't contain enough damning details to prove the law has been broken.
Former MP Jami-Lee Ross is accusing Mr Bridges of mishandling a $100,000 donation from Chinese businessman Zhan Yikun.
On Wednesday he leaked a recording of the pair discussing the donation and has taken a complaint to the police.
Otago University Professor Andrew Geddis said the phone call didn't provide enough evidence Mr Bridges was trying to hide donations.
"What's not clear from the recording is why the donation came in in the way that it did," he said.
"It appears that the donation came from seven different individuals, it's not clear whether those seven individuals have given their own money under their own names... or whether the money's been given using those seven people's names, but actually a different person funding it, in which case there would be problems under the Electoral Act."
Prof Geddis said the phone call did not provide any way to tell which method had been taken.
"Based on this recording alone there doesn't seem to be anything in particular to suggest that there's been a problem under the Electoral Act," he said.
Massey University law professor Chris Gallavin agreed there wasn't much in the call, telling The AM Show it had proved to be a "fizzer".
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"On the face of it there doesn't seem to be anything there actually, we've got to be a bit careful cause we don't want to embroil ourselves within a police prosecution or investigation," he said.
"They might be privy to a whole lot of evidence we don't have, but he certainly talked it up and I think that you and I and all expected there to be smoking gun as I see some reports, or something quite cataclysmic.
"But unfortunately I can't see really anything in there, unless there is other evidence that is yet to come out."
The recording also showed Mr Bridges referring to one of his MPs, Maureen Pugh, as f**king useless, but that didn't surprise Prof Geddis at all.
He told Newshub that MPs are elected by the people, not each other.
"Anyone who's been involved in politics knows that people can be in political parties and not exactly be friends," he said.
Maureen Pugh said on Twitter she's accepted Mr Bridges's apology and the pair are moving on.
Watch the full interview with Chris Gallavin above.
The AM Show with Duncan Garner, Amanda Gillies and Mark Richardson, weekdays 6-9am on RadioLIVE and streaming live to the rova app on Android and iPhone.