Gone by lunchtime: Judith Collins started her day defiant but within hours lost the confidence of her caucus

Judith Collins started the day defiant, insisting she'd still be leader by the end of it, but within hours she was out - a vote of no confidence from her caucus. 

In response to her late night sudden demotion of challenger-in-chief Simon Bridges, deputy Shane Reti has stepped up as caretaker leader, while National MPs line up to challenge for the permanent role next Tuesday. 

They include Christopher Luxon and Mark Mitchell. Bridges is still weighing it up. Collins accused Bridges of saying something inappropriate of a sexual nature to Waitaki MP Jacqui Dean. 

Blindsided, dumbstruck and dazed - the National Party tying itself up in knots. Wounded, National MPs wore their hearts on their sleeves as they arrived at work on Thursday morning. 

"Obviously, it's a traumatic time for us," said National MP Andrew Bayly.

"Just when we get Australian cricket on the backfoot, we go and shoot ourselves in the foot, it's extraordinary," added National MP Ian McKelvie. 

Their colleague Harete Hipango commented: "There's a house that needs to be tidied."

Simon Bridges' brother-in-law did away with the euphemisms completely.

"To make it abundantly clear, I cannot work with Judith Collins as leader and I'm holding over all my portfolios this morning," said Simon O'Connor. "The National Party must get rid of Judith Collins."

Would-be leadership challengers Christopher Luxon and Mark Mitchell played it coy. 

But the drama hadn't even started yet. It all kicked off when Bridges arrived at Parliament where he held an early morning press conference. 

"I'll make it all very clear," he said, when asked what comments he made to his colleague Jacqui Dean that prompted Collins to demote him. 

And did he ever.

"What we saw yesterday was truly desperate stuff from Judith Collins," Bridges said. "I think it shows that she'll go to any length to hold on to the leadership."

His return fire signalled all out war in the National Party - and Collins was ready for battle. She was adamant she'd still be leader at the end of the day. 

"Yes I will."

But what a difference five hours makes. The blue coup banner went up, and by lunchtime, Collins was crushed.

"I'm off for some 'me time', thank you," she said as she departed Parliament. 

When asked how she was feeling, Collins said: "Very good, actually, greatly relieved."

"It's a really hard job," she said. 

Collins made it a whole lot harder on Wednesday night, and perversely - despite the allegations against him - a whole lot easier to bring back Bridges. 

Bridges wouldn't say if he threw his hat in the ring for leadership. But there's a chance he'll go for it. 

"I'm considering this," he said. "The reality is, despite the media commentary, there wasn't a vacancy. I was genuine in my clear statements."

Tuesday is D-Day and until then Collins' loyal deputy Shane Reti is custodian. When asked why the party is dragging it out until next week, Reti said: "Thoughtful decision making is always good."

It seems a bit rich coming from National right now, given it was Collins' late night thoughtlessness for her caucus that was her undoing.

Newshub caught the reaction of National MPs late on Wednesday night after Collins issued the media statement about Bridges. 

"In my view it was deeply disrespectful to the caucus and the caucus should have been brought together and it should have been discussed," said Mark Mitchell. 

"It's been a long day, I'm tired and I'm going home," said Michael Woodhouse. 

"All I want to do is go to sleep," added Harete Hipango. 

Now that's one thing the caucus would agree on - it's time for a nap. 

Who are the likely contenders?

With the list of possible contenders including Simon Bridges, Mark Mitchell, Chris Bishop and Christopher Luxon with Nicola Willis as his deputy - it's very hard to pick. 

The caucus is more divided than it has ever been so it's hard to pick how the factions are lining up or who could get the numbers. But they need to sort it out and soon - leaving it to fester until Tuesday is frankly stupid.

If this whole mess has taught National anything it's that it needs to swiftly and unanimously get behind a single leader and stay in line. Anything less, and this cycle of self-destructive behaviour will continue.

Will Collins cause harm now she's dethroned?

You cannot cage Collins, and when her wild side is unleashed - as was on clear display on Wednesday night - she's even more unpredictable, especially now she's wounded. 

She's staying on as an MP in her Papakura electorate, and she's staying in the caucus, meaning she'll be party to all those top secret squabbles that used to stay behind closed doors.

Whoever the new leader is come Tuesday will have to weigh up a few options to deal with Collins - reward, exile or sleep with one eye open.