Of people who purchased newspapers, the opposition rose to 56.7 per cent.
NZME, which publishes the Herald, and Fairfax want to merge in order to better compete with giants Facebook and Google who take the lion's share of online advertising revenue.
After the Commerce Commission proposed to decline the merger, 30 editors wrote an open letter to the competition body arguing they had got it wrong.
"We decided to write because in its draft decision the commission didn't stick to the economic analysis but strayed into intangibles such as the quality of journalism and unquantified risks to editorial independence, and that is territory where we live and work every day," the letter stated.
Otago Daily Times publisher Allied Press have opposed the merger along with publisher Horton Media.