Labour ministers are giving Winston Peters a nine out of 10 for his time as Acting Prime Minister, but National leader Simon Bridges said he had "bumbled" and focused on sideshows such as the Australian flag at the expense of the economy.

Peters will hand the reins back to Prime Minister Jacinda Ardern at midnight tomorrow when he flies to Singapore for international summits.

Bridges said Peters had not been as bad as some had feared but nor had things gone as smoothly as Labour ministers claimed. He pointed to Peters' comment that the "jackals" would come for deputy leader Paula Bennett and that Bridges would not last until the election, as well as Peters' ongoing crusade against Australia's flag.

"I think he has performed as I expected. He has bumbled along, but ultimately he hasn't changed the course of his direction. He's focused on side issues like talking much more about me, flattering in a sense, and Paula Bennett but not talking about the economy, the decline in business confidence, on job insecurity.

"These are the things he should be judged on and he has done nothing.

"As Acting Prime Minister, in terms of our two biggest trading partners, he's overseen lesser relations. His ministers have called Australian ministers 'venal,' he's fixated on their flag. I know none of that has been good for our relationship."

He said China was also upset by the references to it in the Government's recent defence report.

Peters would not rank himself, saying it "would be an invitation to immodesty". He has defended his criticisms of Australia saying it was "candour" despite accusing former Prime Minister John Howard of interference after Howard described the election result as "unjust".

Finance Minister Grant Robertson and Justice Minister Andrew Little both gave Peters a nine out of 10.

Asked what Peters had lost a mark for, Robertson said that was between himself and Peters. "I think he's done a great job."

Little said it was because he did not like to bestow 10s readily.

"Jacinda is the exception, I would give Jacinda a 10.

"He's been excellent, chairing the Cabinet and keeping everyone going. The great thing is it shows that with this Government, going from Jacinda to Winston and then Winston back to Jacinda, it's been seamless."

NZ First MP Shane Jones gave Peters a 10 out of 10, saying he was initially "plagued" by low expectations from the media but Jones had had no such qualms.

He would not say which media had held those views.

Asked who was better of Ardern and Peters, Jones said "I love my leader, Matua Winston, but I am faithful to my coalition leader, which is Jacinda Ardern."