National Party leader Judith Collins says it is up to her caucus whether her predecessor Todd Muller remains in Parliament for another two years.
Muller last week announced he would retire from politics at the election, citing his health and family. It has since emerged he was pressured to leave after being dobbed in for anonymously badmouthing a colleague to media.
On her way into a regular Tuesday caucus meeting, Collins was repeatedly asked whether it was tenable for Muller to stay on as an MP until the election.
"It's not a matter for me," Collins said. "My personal view is that caucus makes these decisions."
Asked directly whether she had threatened Muller with expulsion during a late night caucus meeting last week, Collins pushed back.
"I can't possibly do that, can I?" she said. "People should know I don't threaten."
Collins declined to answer further questions on the events leading up to Muller's announcement.
"Anything that happens in caucus stays in caucus," Collins said.
Muller spearheaded a leadership coup within National in May last year, ousting Simon Bridges from the top job, only to last 53 days before resigning. He is on leave and will return in early August.
A late night meeting was called on Tuesday last week after Collins learned Muller was one of the unnamed MPs quoted in a Newsroom article critical of returning MP Harete Hipango.
It is understood National MP and former whip Barbara Kuriger alerted Collins because she was with Muller when the comments were made.
Muller was then given an ultimatum during last Tuesday's meeting: announce his retirement or be expelled from the caucus.
Kuriger this morning refused to elaborate on her involvement: "I don't talk about caucus matters and I won't be talking about caucus matters today."
Hipango - who returned to Parliament following Nick Smith's resignation - said she felt supported by her colleagues in the National caucus.
"It's a privilege to be back here and I never take those things for granted," she said. "I'm looking forward to continuing and giving service in a waka with the other members of my caucus."
Hipango declined to respond to queries about allegations of inappropriate spending during the last term of Parliament.
NZ Herald has reported that one of Hipango's staff members raised concerns that furniture - including a television - was purchased with taxpayer funds and allegedly kept at her home.
"We're going to move on from that," Hipango told reporters on Tuesday.
"The matter's been dealt with appropriately by Parliamentary services and I've had their full support. There has been nothing improper or inappropriate about the conduct."