Epsom MP John Banks tried to use Prime Minister John Key's name on his own election hoardings last year - but was foiled when the Electoral Commission ruled it would require National's approval.
The Electoral Commission's advisory opinions show Mr Banks sent in four possible hoardings - all of which used Mr Key's name - in a bid to enhance his chances of winning the seat.
In a letter, Mr Banks told the commission his preferred hoarding was: "A vote for me/ Helps John Key. John Banks Epsom."
Other options included "A vote for me helps a John Key Govt" and "Strategic voting helps John Key. Vote John Banks in Epsom".
Mr Banks had argued that the use of Mr Key's name was not an advertisement for Mr Key or National because Mr Key was not a candidate in the electorate and there was no reference to the National Party.
However, the Electoral Commission said it was a party advertisement for National because it encouraged voters to give their party votes to National. That would require National to provide approval for Mr Banks to use the words and to include some of the costs of the hoardings in its own election spending.
Yesterday Mr Banks said he had not tried to get that approval and no discussions were held about sharing any form of advertising. "We weren't going to ask the Nats for that approval at any stage, so we did not proceed. I wanted a fair fight in Epsom."
Mr Banks won the seat but the relationship between National and Act was a focus of the campaign, highlighted during the now infamous "cup of tea" Mr Banks and Mr Key shared, intended to be an implicit endorsement of Mr Banks for National voters in Epsom.
The advisory opinions also show several groups which were not political parties were stopped from going ahead with some of their election plans. Teachers' union the New Zealand Educational Institute submitted scripts for television and radio advertisements but was told that references to the Government cutting early childhood funding and the words "speak up for education" meant they could not be broadcast because they encouraged people not to vote for National. Strict broadcasting laws meant they could not be played.
Save TVNZ 7 - a group set up to campaign against the decision to cut TVNZ 7 - was thwarted from running a radio ad urging people to "vote to save TVNZ 7" and saying "the bad new is the National Government's going to scrap it".
A radio network was told a Sensible Sentencing Trust advertisement which referred to the trust's website was in breach because the website was likely to contain election material.
Environmental group The Renewables was told the use of "vote for the planet" was too close to the Green Party's slogan in 2008, making it an election ad which would require Green Party permission.
And handing out copies of the Hollow Men book at Wellington Railway Station was ruled to be "treating" - giving gifts to influence voters.