Planned rules governing election hoardings - including imposing a minimum type size - are too prescriptive, say National and Act.
The draft regulations have been circulated by Associate Justice Minister Rick Barker to party leaders for their consideration.
The Government's ability to make regulations governing election advertising is contained in
an Electoral Act amendment passed last year.
The regulations, marked confidential but obtained by the Herald, specify things like lettering size and spacing between lines.
Aimed at road safety, they require letters to be at least 12cm high in 70km/h zones, and 16cm high in areas with higher speed limits.
But for the regulations to be passed, half of the party leaders representing 75 per cent of Parliament's MPs would need to support them.
National MP Murray McCully said the regulations would go to caucus after the party had discussed the matter with Mr Barker.
But he would be "amazed" if caucus supported the rules, which also cover the shape and colour of advertisements and prohibit hoardings liable to be mistaken for traffic signs.
"It seems to be a rather Stalinist approach to political communication. I quite like to think of this as a free country."
Mr McCully said the heavy-handed regulations would also place extra burdens on local councils, which would have to establish a costly process to deal with hoarding permits.
National would need only one other party's backing for the Government lack the necessary support.
Act is keener on the rules, but would only vote for them if the lettering clause was modified or deleted.
Act MP Stephen Franks said he supported the intent of the regulations because he did not want to see the Resource Management Act used by local councils to restrict political activity.
But he said the lettering clause was "nannyish" and unnecessary.
"I'm not aware of any evidence that people seeing political signs and finding the lettering too small would drive off the road."
No-hazard hoardings
* Lettering must be a minimum of 12cm high in 70km/h zones and 16cm high in areas with higher speed limits.
* Hoardings must not be the same shape and colour as traffic signs, or able to be mistaken for traffic signs.
* Hoardings must not use reflective material or be illuminated in any way.
