Amy Adams is the latest National MP to announce a run for the role of party leader, just a day after Bill English resigned the position.
National's caucus has two weeks to decide on a replacement leader, with Mr English's resignation effective 27 February.
Who's in and who's out?
* Judith Collins was first to confirm her tilt this morning
* Simon Bridges was next off the block, confirming before lunch
* Amy Adams confirmed her run this afternoon
* Mark Mitchell is considering a run
* Paula Bennett has ruled out running for leader, but will seek to retain her position as deputy
* Steven Joyce is considering his position
* Jonathan Coleman said he was "not doing anything immediately", but was ruling nothing in or out
* Nikki Kaye has ruled herself out
In a press conference this afternoon, Ms Adams confirmed she would stand as a third candidate, against Simon Bridges and Judith Collins.
Ms Adams arrived at the news conference with Nikki Kaye, Chris Bishop, Maggie Barry and Tim McIndoe in support. All four supporting MPs denied they were seeking the position of deputy leader.
Ms Adams said she loved this country deeply and wanted to create a country her children wanted to grow up in.
She said she believed she was the best person to be leader and reflected the views of a range of people, describing herself as economically conservative and socially liberal.
She said she has had good conversations with other leadership challengers and did not believe the race would become nasty.
'I can hold a government to account': Judith Collins kicks things off
I’m announcing my candidacy for Leader of the NZ National Party. We’re going to need strong & decisive leadership if we’re going to win in 2020. I’m that person.— Judith Collins (@JudithCollinsMP) February 13, 2018
Judith Collins used Twitter this morning to announce her bid, saying the party needed strong and decisive leadership to win the 2020 election.
She said National needed someone who can put pressure on the government, and handle the toughest job in politics.
"So I'm one of the few people in our caucus who's had any experience in opposition and it is not going to be easy but we do need to do that," she told Morning Report.
Ms Collins said the opposition needs to be able to keep the government accountable and she would be able to do that.
"I can hold a government to account because I'm not frightened of a government.
"I can stand up when I need to and I also am somebody who understands that it's actually the people of New Zealand that counts, not us [politicians], it's not our feelings it's their feelings."
Ms Collins said she was approached by people from caucus during the Christmas break because they were concerned that Mr English might want to leave at some stage.
"My view at that stage was ... I wasn't going to do anything that would undermine Bill because he deserved respect, and he deserved to work things out himself."
The leadership competition should be about who can win in 2020 rather than just more of the same, Ms Collins said.
"I think it's really important that we have a really full and robust debate in the National Party caucus, I don't think that this caucus should stand by and just let things slip along.
"This is going to be the fight of our lives for 2020 and I'm the person to do it."
National needed the strongest possible opposition because although it had the numbers, that did not necessarily translate into winning, Ms Collins said.
Opposition was very different from government, she said.
"I think it's really important we have the strongest most decisive leader we can because there is no doubt about it, the Prime Minister Jacinda Ardern is a formidable, formidable person for us to deal with.
"We would be very foolish to underestimate her - I don't."
"We do need to renew and refresh" - Simon Bridges
Simon Bridges confirmed his own intention to run at a media conference at 11am.
He said some of his colleagues had asked him to run, but would not name names, saying it was "only natural".
"We do need to renew and refresh."
He said he had the highest regard for other contenders, who were all capable, and it would "absolutely" be a clean contest.
"I am focusing on Simon Bridges", he said.
He said the next leader needed to be both a good opposition leader and an alternative Prime Minister.
While he could not say if he had the numbers to take the leadership, he felt he had a lot of support. He also said he could work with current deputy leader Paula Bennett.
Mr Bridges said he had some ideas for policy changes, but would not go into details today. There would be a focus on evolving the party and moving with the times to push for a National government in 2020.
He said he represented a generational change, which was even more important today with Jacinda Ardern as Prime Minister.
He agreed with Judith Collins that the Labour government was guilty of "virtue signalling".
Asked about his biggest weakness he said he was in danger of being a bit earnest.
Steven Joyce 'taking some soundings'
Mr Joyce said he was canvassing support among the caucus and party members before deciding whether or not to run as leader.
Mr Joyce was National's campaign manager and a Finance Minster in the previous government.
He said he was considering his position.
"I'm taking some soundings from colleagues, but also party members and supporters and people who voted for us... We've got a big responsibility to put together the best team we can for 2020."
His interest in the leadership was about challenging the government, rather than any personal ambition, he said.
"That's not really my gig. My view is always to be focused on delivering for the public and that's what as a team we have to do."
Mr Joyce rejected any suggestion he lacked credibility after running the $11.7 fiscal hole line against Labour during the election campaign
"I don't think it makes any difference to be honest. The new government has an incredibly tight, straightjacketed budget because of what Mr [Grant] Robertson insisted was the situation before the election - and he's going to have to deal with that."
He also questioned the "new generation" tagline being used by other leadership contenders, most notably Mr Bridges.
"We all represent different aspects of our base, but we're all actually quite similar ages, between 40 and mid-50s; there's not a lot of difference between the announced candidates so far".
National needed to push back strongly against any government attempts to impose a capital gains tax, restrict negative gearing for people who own a second property, or employment law changes, said Mr Joyce.
Paula Bennett not seeking leadership
Mrs Bennett announced on Facebook she would not be seeking the National Party leadership.
"I believe it's in my role as deputy where I have the most to add.
"Our new leader will need help from an experienced, loyal deputy and I offer that."
She said the party was "united and strong" and the selection of the new leader would be "robust but respectful".
Coleman not ruling anything out
Jonathan Coleman said he was "not doing anything immediately" and was ruling nothing in or out.
"The important thing is that National can win in 2020 and we've got to get the right leadership combination to make sure we've got the best possible chance of victory."
It was important the caucus came out of this contest united, Dr Coleman said.
"Ideally you'd have a proposition everyone can live with and get behind, but this is politics and everyone has the right to enter the race and there'll be a range of views across the caucus."
MP Mark Mitchell has confirmed he is considering a run for the leadership.