It is a three horse race for Prime Minister, with Judith Collins, Bill English and Jonathan Coleman all wanting to replace John Key.
Jockeying has begun for the position left vacant by Mr Key following his shock resignation on Monday.
The National Party caucus met on Tuesday to discuss the rules of the contest and for contenders to make themselves known.
So far, Finance Minister and Deputy Prime Minister Bill English, Police and Corrections Minister Judith Collins and Health Minister Jonathan Coleman have confirmed they want to lead the country and the party in a post-Key era.
Mr Coleman was the first to confirm his bid to become the party's new leader.
"It is a job I've been thinking about for a long, long time."
"I am seeking party leadership and I am absolutely up for the challenge. I believe I've got the energy, I've got the relative youth on my side, and I am absolutely focused on winning this leadership contest.
He paid tribute to what Mr Key and the Government had done over the past eight years.
"It really is time to build on the gains of the last few 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, it's going to need new personnel - so combining the best of the current line-up and those who are coming through the caucus."
He touted his decade in politics - including defence and associate finance portfolios - and his previous career as a doctor.
He did not answer questions about who else put their hands up in the caucus meeting.
Mr English, who has Mr Key's full backing, also announced his candidacy to reporters, saying the country has "huge opportunity" ahead of it.
"We've got choices over the next five to 10 years most countries don't have. I've been intimately involved in the policies of a John Key-led government. I can see fantastic opportunities for a stronger economic performance, of spreading the benefits of growth for all New Zealanders."
He says he hadn't thought about who might be his deputy, or if he'd serve as a Finance Minister under another Prime Minister.
In 2002, Mr English led National to a drubbing in the general election - he says things have changed.
"You learn as much from losing as you do from winning. National is different, the political environment is different."
Ms Collins says the party needs someone who can "connect to New Zealanders, whether they're men, women or of any ethnicity".
"I believe I can do that.
"I think it's important that the best people for the jobs get them and I happen to think I'm one of those people."
Ms Collins says she wouldn't put her name forward unless she thought she had a "very good chance" at taking the party to victory in the 2017 election.
But there's still time for other contenders to put their hands up - the caucus won't vote until December 12.
Prior to the meeting, Transport Minister Simon Bridges wouldn't rule out a shot at the title either - even calling out his boss.
"The National Party has got a huge amount of depth and we're bigger than one person even John Key."
He said it was an important task the caucus had in front of them.
"Obviously we're not just deciding the leader and the deputy leader of National, we're deciding the Prime Minister and Deputy Prime Minister."
If not himself, he wasn't giving any clues as to who he might back.
"I think I'm going to keep my powder dry and what's important to me is that we go in and decide in there.
"These issues are far too important to be dealt with in the media."
Meanwhile, Economic Development Minister Steven Joyce says he doesn't want the leadership or deputy leadership roles, however Finance Minister was a different story.
"I've never had much in the way of leadership ambition and that hasn't changed," he said.
"I just think caucus has got to have the opportunity and space to make a call."
Mr Key says he'll stay on as MP for Helensville once he steps down as Prime Minister until nearer next year's election to avoid a by-election.
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