"When the incumbent stands down it certainly makes it slightly easier, but we will still have to work incredibly hard with a strong work ethic. We have a good campaign plan in place but I will still have to earn the right to represent Napier."
Mr Nash said his opponent had done a good job as Napier MP.
"At the end of the day he is, I think, the first cabinet minister to come from the Napier seat and I think he has represented Napier well in Parliament."
National Tukituki MP Craig Foss said it was a "shame to lose a good mate" and "half of the Hawke's Bay team" but respected his decision and wished him the best.
He said it was too early in the process to know who would be the next Napier candidate and hadn't heard of any names yet.
Mr Tremain said he was proud of the significant achievements of the John Key led government as well as his own personal highlights during his political career.
"Politics is a very up and down game but I am very positive about my time in government."
"Winning Napier three times in a row was a highlight. Most people never thought we would win the Napier seat let alone win it three times." he said. "Becoming senior government whip, a minister outside cabinet and then a cabinet minister are highs as well, but continuing to represent the people of Napier and Hawke's Bay is one of my proudest achievements."
He said he would continue to represent the community until the next elections.
"I will prioritise the second tranche of local government reform, gambling reform, fire legislation and the ICT Strategy and Action Plan in my ministerial portfolios between now and the election."
The son of former All Black flanker Kel Tremain said he was looking forward to spending more time with his family and three teenager children.
"My age at this point I think it is the best decision for me and my family - I've been in this game for nine years, over a quarter of my working life.
"My family has been a huge part of my decision. I have three children finishing high school and I want to devote more time to them before they leave home," he said.
Hastings Mayor Lawrence Yule said Mr Tremain would be a big loss to Parliament and had given it all to Hawke's Bay and Napier for the last nine years.
"I have tremendous admiration for Chris. He is a very successful businessman, has a wonderful family and is a very well balanced individual."
Mr Tremain was not prepared to tip or name anyone to become the National representative for Napier after his departure, but said the timing of his decision had left the party a chance to find a strong candidate. "One of the key reasons I have made this announcement now, which has come to many as a surprise, is so a good strong new candidate can be chosen to represent Napier in the next elections. There will be a good search for the right person for the job until January, February."
He said despite holding the Napier seat for three terms, after more than 50 years of Labour dominance, he did not expect his departure would lead to a National Party demise in the Art Deco city.
"Even when I first stood for the Napier seat people have said I wouldn't win. People have said I would always be beaten by a Labour candidate, but Napier is no longer a Labour seat."
