UPDATED 6.10pm Health minister Jonathan Coleman has confirmed he is standing for party leadership.

Coleman said: "I sense an appetite in the caucus for change."

LISTEN ABOVE: Health Minister Jonathan Coleman spoke with Larry Williams

Earlier this morning, Coleman said he wanted to sound out opinions on whether there should be a contest to replace John Key.

"I would not put my hand out unless there was considerable appetite for a contest of ideas across the caucus."

Coleman would not name a possible deputy on his ticket, but when asked if Amy Adams would provide the female and South Island balance said he would like to work with her.

He would not say who else was running, but did expect it to be contested 

National minister Judith Collins is still refusing to show her hand on the party's leadership as National MPs head into a caucus meeting for initial discussions. 

Former National Party leader Don Brash backs Collins for the leadership.

Education Minister Hekia Parata said she would back English.

"I'm not precluding that there will be a contest, I'm just saying I think he is best for the role of that's what he decides to put his name forward for."

She said English offered predictability and certainty and was known for his sound management of the economy.

"I think he's got a great set of values."

She would not say if anybody else had rung her or who she would back for deputy.

Paula Bennett, who is Key's preference for deputy leader, said she would wait to talk to caucus before commenting.

She said she was "devastated" Key was leaving.

"So I'm still in that kind of place to be honest. He's the greatest leader I've ever known and ever seen and I'm just going to miss him, actually. I'm going to miss him as a leader and miss him as a Prime Minister and miss him as a man really."

Newstalk ZB political reporter Felix Marwick said Louise Upston, Nathan Guy and Michael Woodhouse have declared for Bill English.

"Nick Smith and Simon Bridges are keeping their own counsel. Steven Joyce isn't chasing anything."

Justice Minister Amy Adams refused to say if she would put her name forward.

"It is something we will discuss in caucus and I'm not intending to play all that out in the media."

Transport Minister Simon Bridges did not rule anything in or out.

"I think I'm going to keep my powder dry and go in decide in there. I want a good discussion in the caucus room. These issues are far too important to dealt with in the media."