National Party leader Christopher Luxon says the party and the public can trust his account of the investigation into Tauranga MP Sam Uffindell.

Luxon has a faced a day of questioning about why he won't release the terms of reference that shaped the investigation, led by lawyer Maria Dew, KC, into bullying allegations against Uffindell.

He has also refused to release an executive summary from Dew, even to his own caucus.

Luxon insists he has fairly communicated Dew's conclusions, and says: 'Everyone trusts Maria, and they trust me. They trust me to represent the findings”.

But Acting Prime Minister Grant Robertson says there's no reason not to release an executive summary.

'We did release an executive summary when Maria Dew did an inquiry for us, and I would expect that you as media and New Zealanders would want the same from Christopher Luxon.”

In 2019, the Labour Party commissioned Dew to investigate an alleged sexual assault by a staff member at a party camp. It released her eight-page summary.

National MPs met to discuss Uffindell's future with their caucus on Monday, but they were not given the report – or even its executive summary – discussing his conduct and allegations of bullying.

Nevertheless, the embattled MP's caucus colleagues defended Uffindell on Tuesday and said they had faith he was 'reformed”.

Bay of Plenty MP Todd Muller says Maria Dew's report has 'vindicated” Uffindell, but he says he hasn't seen her report or its executive summary.

Announcing the outcome of this investigation, National Party president Sylvia Wood says Dew has not 'substantiated” the claims from Uffindell's former flatmate.

The specific claim was that, while Uffindell was a student at the University of Otago in Dunedin, he banged on his flatmate's door while screaming obscenities at her. The former flatmate told RNZ he bullied her with insults such as 'Hit the road, fatty.”

Although Dew has not responded to questions about her investigation, Luxon says she's comfortable with the way his party is portraying it.

'All the statements that Sylvia, myself and Sam read out yesterday were actually all run through Maria Dew as well,” he says.

'They were a faithful representation, and she was comfortable we were communicating the findings of her report.”

A number of National MPs confirmed they did not receive Dew's executive summary on Monday and relied on the party leadership's reporting of what Dew had concluded.

Luxon says Dew found there was a 'fractious, deteriorating flatting relationship”.

But he says she concluded there was 'no ongoing bullying pattern” from Uffindell after he left King's College as a teenager.

Uffindell, on Monday, says her investigation found 'the incident did not occur as reported in the media”.

At King's College he attacked a younger student, joining with a group of 16-year-olds to assault a 13-year-old in the middle of the night.

The victim says they came into his dorm room and hit him with wooden bed legs. Uffindell acknowledged the attack, saying he was 'a thug”, and he told National about it before being selected as its Tauranga candidate.

Luxon says the terms of reference will not be released, but he outlined the 'objectives” of the investigation.

'One was to get clarity and conclusion around the events in Otago,” he says.

'Secondarily to make sure that, subsequent to King's College, there was no ongoing pattern of bullying behaviour.”

-Glenn McConnell/Stuff.