Winston Peters takes cheeky dig at Simon Bridges over potential leadership challenge from Christopher Luxon

Winston Peters has taken a cheeky dig at Simon Bridges in Parliament today over a potential leadership challenge from Christopher Luxon.

Former Air NZ boss Mr Luxon was selected as National's candidate for Botany on Monday night, with many tipping him as a future National Party leader.

Mr Peters was filling in for Prime Minister Jacinda Ardern during question time when the exchange between him and Mr Bridges took place.

"When will there be an extra 263 frontline case managers in place as she claimed yesterday?" Mr Bridges asked, referencing comments made by Ms Ardern around extra staff at Work and Income NZ.

"On behalf of the Prime Minister, just as soon as we can get the process completed," Mr Peters answered before being interrupted.

"I suppose we've got Mr Luxon to thank for you being here on a Thursday, but shouting and jeering at me won't help," he continued, alluding to a potential leadership challenge from National's high-profile new candidate.

"In fact it's quite the contrary, this is like having a dual of wits with an unarmed opponent. My point is the process will take time and obviously it's aspirational but we will get there," Mr Peters concluded.

Mr Bridges and Ms Ardern often don't attend question time on a Thursday.

Mr Bridges went on to ask if Ms Ardern would correct the record over her WINZ staff numbers after Social Development Minister Carmel Sepuloni said only 170 of the 263 extra staff might be introduced this year.