A group of prominent New Zealand authors, including Margaret Mahy and C K Stead, have come out in support of retaining MMP.
At the general election later this month voters will be asked whether they want to retain MMP.
They will also be asked which of four other systems they would prefer if MMP were scrapped.
If more than half of voters choose to keep MMP, the system will be reviewed. If not, a second referendum to find an alternative will be held in 2014.
Campaigns for and against the two systems have begun.
The 20 writers have joined former All Black Anton Oliver in supporting the Keep MMP campaign. Novelist and poet Fiona Farrell said she believed MMP offered diversity and meant everyone's vote counted.
Philip Temple, who organised the group, said the authors liked MMP because it required consensus rather than conflict, but that was not to say it couldn't do with improvement. Most of the group supported retaining the system but would like to see it reviewed and tweaked, he said.
"I think the fact that these people are a significant part of our social and cultural life and are saying we support MMP, we think we should keep it, should indicate to people how representative MMP is of our society."
Temple became interested in the electoral system in the 1980s when he grew tired of the way politics was going. In 1990, he began travelling to Germany and saw the alternative in action there. He also noted how writers in Europe were consulted and spoke on a number of issues.
"Writers tend to reflect and often represent the views of society, or who we are. In a way, they kind of broadly represent a whole lot of New Zealanders."
Some in the latest group, including Maurice Gee and Fiona Kidman, also supported MMP during the earlier referendum.
Temple said he approached a diverse group of writers around the country. Just one, whom he declined to name, refused to participate.
"Really, most of these people said 'yes' straight away or pretty soon after."
Crime writer Vanda Symon supported MMP because it worked and she believed there hadn't been enough public debate about the matter. The way government was voted in was an important issue and had not been taken seriously enough, she said.
People could relate to the writers when they said they wanted their vote to count and to make a difference. "We're the everyday man. We're not politicians, so it's not affecting our livelihood as it were."
- Sunday Star Times