ACT's leader says everything is negotiable - as speculation about him becoming the next Finance Minister, if the coalition return to power continues to swirl.

National leader Chris Luxon says his party keeping that portfolio is non-negotiable.

David Seymour says the coalition need to ask themselves what the best configuration is to make sure they have a fighting chance of a third term in three years time.

"Now, I'm not particularly wedded to myself being in any particular position, but what I do take exception to is this tone that only National ministers can do things competently." 

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