David Seymour says the Prime Minister would have a tougher job sacking a minister from ACT than from National.

Luxon stood down Melissa Lee and Penny Simmonds from portfolios last week.

Seymour says it would take a bigger process if Luxon wanted to give the boot to one of his party's ministers.

"What I did say is- if we were going to have that sort of action, then the coalition agreement requires good faith, it requires conversation - and it ultimately requires agreement on these sorts of things."

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