The Green Party says a campaign of scaremongering by opponents of the Electoral Finance Act is discouraging participation in political debate.
In a speech, Electoral Commission chief executive Helena Catt said uncertainty over the Electoral Finance Act during the regulated period ahead of the election has had a "chilling" effect on participation in political and campaign activity.
Dr Catt also said the meaning of significant sections of the new legislation are unclear, which is burdening the commission beyond its resources.
Accordingly, she says the commission is not confident it will be able to reach informed positions on the interpretation of some provisions within the election period.
The Greens supported the Electoral Finance Act on the condition its impact be assessed by a citizens' assembly, and an independent review be held.
Party co-leader Russel Norman says many of the commission's concerns may have been avoided if the law had come into effect in April rather than January.
He says campaigners against the law have made people worried about what they can and cannot say.
John Boscawen of the Freedom of Speech Trust led a campaign against the bill and is now an ACT party candidate. He says the Greens are in denial about the effects of the law.
He says a number of organisations are too frightened to get involved in the election campaign.
Assault on democracy, says National
The National Party says comments made by the chief executive of the Electoral Commission about recent law reforms are worrying in the extreme.
Leader John Key says the comments confirm the party's worst fears about the legislation - that it is an assault on democracy and is unworkable.
Justice Minister Annette King is refusing to comment.