Policy proposals put forward by a National Party taskforce include a referendum on the monarchy, the future of Maori seats and reducing the number of MPs to 99.
The ideas are part of National's attempt to revamp itself and will be debated at the party's annual conferences starting later this week.
Under the proposals, a referendum on the monarchy would be held after the death of the Queen.
National's leader Jenny Shipley says the issue is important to New Zealand's future direction.
Prime Minister Helen Clark says she personally believes NZ will eventually become a republic, but she says the Labour-Alliance Government has nothing on the agenda at the moment.
Shipley says she accepts that any suggestion of abandoning the monarchy would be a reversal of the party's traditional conservative position.
The taskforce also favours cutting the number of MPs to 99, although it is divided over whether to abandon the Maori seats.
Meanwhile, Royalists are criticising National's suggestion to hold a referendum on the monarchy when the Queen dies.
The Monarchists League of New Zealand, which wants to keep the current system, says it would go against the core values of the party.
President Noel Cox says if the National Party supports keeping the monarchy, then there is no reason to have even a debate on holding a referendum.