Simon Bridges is promising to bring back a ban on prisoner voting, if the Government were to make any changes to the current law which stops those in jail from casting votes.
A new report from the Waitangi Tribunal found the blanket ban on prisoners voting discriminates against Māori, who make up more than half of the prison population.
National say the question of removing the ban is not "a legal question, it's one of values".
"If you've done a crime serious enough to go to prison you lose the right to vote while you're there and that’s still our position," leader Simon Bridges said.
Mr Bridges agreed that in New Zealand prisons, "disproportionately people there are Māori and that’s a complex difficult issue all Governments will want to grapple with".
"But, that’s a different thing from saying a law is racist, it isn't, it isn't aimed at Māori.
"It's aimed at the fact that if you do a serious crime serious enough to go to jail, you lose your right to vote while you're there."
He said National, who brought the ban for all prisoners to vote in 2010, would continue to oppose any changes.
"If we had the privilege to be Government we would change it back. We think it’s absolutely basic and right, if you've done anything serious enough to go to jail, you lose privileges, rights and liberties."
Prime Minister Jacinda Ardern said Government needed to respond, but could not pre-empt what it would do.
"There's an accumulation of reports saying the law was wrong, the law change shouldn’t have happened, and now work needs to be undertaken to see how we address that.
"Our view back then was the law should never have changed."
When asked if they would give voting rights for all prisoners, Ms Ardern said, "we’ve never had that policy".
Before National's changes, prisoners with less than three years of their sentence remaining were able to vote.
"The policy for allowing prisoners with three years or less (to vote) had grounding. It was to ensure those who actually would go back into New Zealand society within the course of an electoral term would be able to vote on the Government they would live in their community under."
The Green Party have reaffirmed its position on the ban, calling for the overturning of the law so all prisoners could vote.
Justice spokesperson Golriz Ghahraman described the ban as "an unacceptable breach of their fundamental rights".
"As a result they are excluded from processes that engage them in society, making their long term rehabilitation harder."
Human Rights Commissioner Paul Hunt said the findings that it disproportionately affecting Māori and breaching Māori rights under Te Tiriti "raises concerns under our international human rights obligations".
Justice Minister Andrew Little told RNZ the law needed to be looked at.
"Up until now addressing this issue hasn't been seen as a priority, but I think the benefit of the Supreme Court decision and now with the Waitangi Tribunal report - it is an issue we have to consider."
He said Cabinet would be considering either completely removing the ban on all prisoners, or returning to the previous law which ruled those with less than three years on their sentence could vote.
The Waitangi Tribunal report today found the Crown to be in breach of Waitangi principles, and called for all prisoners enrolled to vote by the 2020 general election.
Earlier, a High Court ruling found National's 2010 amendment to the Electoral Act, disenfranchising prisoners, did breach the Bill of Rights. This was appealed to the Supreme Court.
The Supreme Court upheld the High Court's findings. It stated that courts do have the power to rule laws inconsistent with the Bill of Rights Act.