National MP tipped as a leadership challenger Erica Stanford has finally given her full backing to the prime minister - having earlier refused to answer the question.

The confirmation comes the day after a crisis caucus meeting at Parliament where Christopher Luxon won a make-or-break confidence vote in his leadership.

In a statement to RNZ, Stanford said the prime minister continued to have her full support - "as he always has".

"The caucus is 100% united behind the prime minister. As a party we are focused on fixing the basics and building the future for New Zealand."

On Tuesday evening, Stanford met reporters with stony silence at Wellington Airport, as they repeatedly asked her whether she had confidence in Luxon.

Prime Minister Christopher Luxon and Education Minister Erica Stanford. Photo: RNZ

Former Cabinet minister Chris Penk has been publicly blamed and punished for the failed coup, but National sources have also connected Stanford to the attempt.

This is Stanford's first public comment since National's three-hour caucus meeting, but she was one of the MPs standing behind Luxon when he confirmed he had won.

Earlier on Thursday, political commentator Janet Wilson told Morning Report Penk was the "fall guy" and there were senior ministers involved in the challenge.

"I hear [Chris] Bishop is somewhere in there trying to manoeuvre," she said. "When you get that kind of manoeuvring, it's deeply divisive."

Speaking to media from Wellington on Thursday morning, Bishop insisted Penk was alone in his challenge and "working for himself".

He said time would tell if the fallout would impact National's chances of remaining in government at the upcoming election.