Jami-Lee Ross has been sectioned to an Auckland mental health facility, following a tumultuous week in which he traded insults and allegations with the National Party and came clean to his wife about extra-marital affairs.

Ross was picked up by police on Sunday, and a source close to Ross told the Herald that Ross was "not in good shape" and "had been sectioned ... people who go willingly aren't sectioned".

Under the Mental Health Act, a person can be sectioned to a safe place against their will and given treatment if their safety is considered at risk.

"He feels terribly alone. He hasn't been home," the source said.

It follows a week of unprecedented political turbulence in which Ross, a former member of the National caucus' senior team, quit the National Party, was expelled from caucus, traded insults and accusations with Simon Bridges and Paula Bennett, and admitted to extra-marital affairs that have rocked his marriage to Lucy Schwaner, with whom he has two children.

It is understood the National Party is continuing to offer Ross support, though it is unclear it if was involved in Ross' admission to the facility.

"Over the past several weeks the National Party has taken seriously the mental health concerns raised by Mr Ross and the medical professionals he has been involved with," a spokesperson for the party said.

"That has included seeking advice from medical professionals and involving police wherever necessary to ensure support is made available to Mr Ross."

But the source told the Herald that the National Party was warned about pushing Ross too far on Monday, when Bridges and Bennett met with Ross about the PwC inquiry into Bridges' leaked travel expenses.

Concerns were raised about Ross' mental health three weeks ago, when Ross took leave from Parliament for "personal health issues" and later said he had a mental breakdown over being accused of inappropriate behaviour towards women.

Ross' doctors were in contact with Bridges and Bennett and, the source said, "were told if any more pressure or stress was headed his way, there was a real likelihood of this incident [being sectioned] occurring".

"Two weeks later, when they confronted him about the report of the leak, the medical advice was reiterated. And they said they were going to release the information in half an hour."

Asked to comment, a National Party spokesperson said: "Mr Ross's mental health has been taken seriously throughout this process, including seeking advice from his medical specialists."

In the weeks following Ross' leave but before this week, it is understood that Ross' doctors told the National leadership team that Ross was doing better and could return to work.

This week, as Ross fronted media, he repeatedly said that he was healthy, even after four women spoke to Newsroom about what they called bullying and intimidating behaviour from Ross, followed by two more women.

Ross disagreed with the way the women portrayed him in the media, but admitted to extra-marital affairs - including with a married MP - and said he had apologised to his wife.

Asked in his last media interview on Friday about mental health issues, Ross said: "I'm okay right now."

National Party pollster and kiwiblogger David Farrar said that Ross had obviously been under "huge stress" as events escalated last week.

While it was unfortunate to hear of Ross' mental health issues, he hoped this would be a chance for "deescalation, and focus on looking after themselves".

I hope Jami-Lee gets good support from both medical professionals and his friends. He has obviously been under huge stress and time for everything to calm down a bit. https://t.co/UVCBRoJ9UW — David Farrar (@dpfdpf) October 21, 2018

Farrar said that the women speaking out would have exacerbated an already difficult situation.

"But also during the week, you think you have to strike back and defend yourself, and only in the weekend, as you come down from that, do you think about the terrible personal cost.

"Let's worry about Jami-Lee's health. There are obviously still issues to be resolved, but not in the next days, or weeks even. That doesn't mean good outcomes for all those involved in the medium term, but it's an opportunity for things to calm down."

Bridges and Bennett have both spoken about Ross' mental health in the past week, but in cautionary tones.

Farrar said this was a very fine line to walk.

"Some people use mental health as a stigma, so for politicians it's challenging to express concern for someone's mental health and not come across as denigrating them as crazy. That's why they have expressed concerns, but in a restrained way because they haven't wanted it to be seen as an attack."

Ross, however, did see it as an attack and pushed back, saying that neither Bridges nor Bennett should be raising his mental health issues because his doctor had called them to tell them he was fine.

Ross' leave from Parliament at the start of the month followed a text message concerned about the mental health of the person who leaked Bridges' travel expenses. It led to speculation that Ross was the leaker, which he denies, though he admitted to leaking details of the text message to media.

An inquiry by PwC, ordered by Bridges and independently reviewed by John Billington, QC, found that Ross was likely the leaker, but was inconclusive.

WHERE TO GET HELP:

If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call 111.

• Lifeline: 0800 543 354 (available 24/7)

• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)

• Youthline: 0800 376 633

• Kidsline: 0800 543 754 (available 24/7)

• Whatsup: 0800 942 8787 (1pm to 11pm)

• Depression helpline: 0800 111 757 (available 24/7)

If it is an emergency and you feel like you or someone else is at risk, call 111.

There are lots of places to get support. For others, click here.