Health Minister Jonathan Coleman has thrown his hat as National leader saying there was a "significant appetite" in National's caucus for "a change from the status quo".
Coleman said he could offer generational change and it was clear there was a desire for a contest over the leadership rather than simply rolling it over to deputy leader Bill English.
He said after National's caucus meeting and sounding his colleagues out last night he had decided to run in the vote, which will be held next Monday. He said he told English before the caucus meeting this morning.
"We need to do what's best for the country as a whole and after taking those soundings, and it's a job I've been thinking about for a long, long time, I am seeking the party leadership.
"Everyone in caucus has a vote but I've done some soundings and there is significant appetite there for regeneration and renewal."
In a clear bid to paint himself as the fresh face compared with English, he said he was "relatively young" and although he had been in politics for 11 years he was "not a professional politician".
He had come from a background as a medical doctor and consulting business.
Although Coleman did not mention English, it was a clear reminder English has been in Parliament since 1990, when he was 29.
"I believe I've got the energy, I've got relative youth on my side and I am absolutely focused on winning this leadership contest but then going on and delivering the very, very best for New Zealanders."
Coleman also pointed to his experience in portfolios from health, associate finance and defence.
He said there was a united feeling of sadness in caucus about Key's departure. "We've seen the private side of him and I can't speak highly enough about him. But it really is time to build on the gains of those past eight years and the question before caucus is, how do we best do that?"
"I feel it needs generational change, it's going to need new thinking in policy areas."
He also indicated a major reshuffle was on the cards if he became leader.
"It's going to need new personnel, so combining the best of the current lineup with those who are coming through the caucus."
He would not say who his preference for deputy would be, but when asked if Amy Adams was a good balance as a woman and South Islander, said: "Amy is definitely someone I could work very, very well with."
He said an early election was not necessarily needed to seek a fresh mandate. Key had set out a very strong policy platform. "If I am fortunate and privileged enough to be leader, I will be focusing on those things that matter to that broad middle swathe of New Zealanders."
Coleman said it was important that the entire caucus backed and supported the new leader, whoever was elected. However, it was also important they could explore a range of options.