Prime Minister Jacinda Ardern has confirmed she'll be making changes to her Cabinet this week but is staying tight-lipped about which Ministers are facing a move.

The PM is set to reveal her first Cabinet reshuffle after delaying earlier in the year and today confirmed it would be announced on Thursday, while continuing to play down the magnitude of the changes coming.

"I consider them to be relatively minor," she told reporters in Wellington.

Ardern wouldn't say who she had spoken to, provide details of the process taken, or hint at who might be moving up or down.

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"Ultimately they're my decisions," she said.

With the Government's flagship Kiwibuild programme struggling, questions have been raised about whether Transport and Housing Minister Phil Twyford may be moved.

But pressed on whether she still had confidence in Twyford on Monday, Ardern leapt to his defence.

"He's done an incredible job with a very difficult area of work ... No government has had to do this before or tried to do this before," she said.

"We are now building more houses than any Government has since the 1970s. I'm proud of that. It's extended across transitional housing, Housing New Zealand, public housing spaces and homeless and that's happened under Phil Twyford."

Labour's Kris Faafoi, who holds a number of portfolios outside of Cabinet, is widely expected to be promoted on Thursday, filling a vacancy left by Clare Curran who resigned in September.

Another hole was also left with the sacking of Meka Whaitiri, after a report into an alleged assault against a staff member, although it's not clear if the spot will be filled this week.

The reshuffle will be the first since the Government took power and was originally set to take place early this year, before being bumped back to after the Budget.

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