"That is a very long conversation and if there is change, it has to be on the basis of consensus. We can't just force change on New Zealanders."
Although Australia has a three-year term, many European countries have four or five-year terms, as does the United States.
Mr Key also indicated that even if National's coalition with the Maori Party ended in 2014, abolishing the Maori seats would not be the priority it had once been for National. The issue has been shelved since 2008 under that coalition arrangement.
"The risk here is that if you rush that process, you could really open up a Pandora's Box of angst and anxiety that will probably naturally find a conclusion to this issue in time. I just don't think we should cause disharmony and issues around race relations over that issue because it's just not significant enough."
The review began in 2010 and is being led by Deputy Prime Minister Bill English and Maori Party co-leader Pita Sharples who have appointed an advisory panel to consider it. However, there is no report date, and Mr English told iwi leaders at Waitangi that "it will take as long as it takes".
He said it would be some time before any recommendations were made - and even then the Government might not act on them if it could not secure widespread agreement.
Mr Shearer said Labour did not believethe Maori seats should be abolished. However, he stopped short of saying they should be entrenched, saying that while he would not want to see the seats in danger, the Maori Party coalition with National had made them more secure.
Asked about a four-year term, Dr Sharples said he did not want to be seen pushing any particular line.
"But I think a lot of people are thinking that - a lot of Maori are thinking that. I don't know if it would wash with New Zealand society as a whole."