Prime Minister Jacinda Ardern stops short of sacking House Speaker Trevor Mallard

Parliament is in clean-up mode after the wheels came off entirely during an explosive late-night session. 

Prime Minister Jacinda Ardern is fuming and scolded House Speaker Trevor Mallard on Wednesday for re-litigating sexual assault allegations against a former parliamentary staffer who he'd already falsely accused of rape.

But the Prime Minister stopped short of sacking Mallard to the horror of the National Party which has labelled him a disgrace and a bully. 

There was barely a peep from Mallard on Wednesday when Newshub approached him for a response. He said he's prevented by court suppression order and mediation agreement from commenting outside the parliamentary process. 

On Tuesday night, under the legal protection of parliamentary privilege, it was a very different story. 

"The member might think that serious sexual assault and not supporting the victims of it is funny, but I don't, Mr Bishop," Mallard said, doubling down on allegations of sexual assault against a former parliamentary staffer he'd already falsely accused of rape. 

The Speaker has been avoiding talking about the man who successfully sued Mallard for defamation, costing the taxpayer $300,000. 

"His career has been ruined; his life has been ruined," said National MP Michael Woodhouse. 

Mallard responded: "That man's life was destroyed when he sexually assaulted a woman."

Labour accused the National Party of victim-blaming, drawing emotive comparisons.

"It sounds like she asked for it; her skirt was too short, she was drunk," said Labour MP Willow-Jean Prime. "I didn't like what I heard."

National's Chris Bishop threatened to take the fight outside - a street brawl where there's no legal protection.

"I'll say the Speaker is a bully and if he sues, I'll say it outside Parliament, and if he sues me I will turn up to court and I will defend it, and guess what? I will plead truth!"

It was a gloves-off, bare-knuckle battle. 

Bishop described Mallard as a "disgrace of a Speaker", who "displayed petulance and contempt and hate".

And it went on, with National leader Judith Collins shaking with rage as she landed the final blow on fight night. 

"I think that was extraordinary," she said. "I've been in Parliament almost 20 years. I've never seen anyone behave like that."

She described Mallard as "the biggest bully in Parliament". 

Collins wrote to the Prime Minister on Wednesday saying the Speaker has got to go. 

Ardern responded: "In my view, in the House yesterday, neither side covered itself in glory."

She said of Mallard: "He did not conduct himself in Parliament appropriately yesterday. He did not meet my expectations nor did he meet his own."

Ardern hasn't met National's expectations either.

"The Prime Minister has delivered a slap on the wrist to Trevor Mallard when she should have delivered the sack," said Collins. 

Ardern responded: "Calling for resignations does not resolve those issues. No one was covered in glory. We need to sort it out."

It's a lot to sort because the Speaker is supposed to set Parliament's standards. 

Standards that have hit an all-time low.