National leader Simon Bridges says the ban on prisoners' right to vote isn't a legal issue, but a question of values.
Justice Minister Andrew Little revealed on Saturday that inmates serving sentences shorter than three years will have their voting rights restored ahead of the next election.
"We plan to make this change in an Electoral Amendment Bill before the next election, so that people sentenced to less than three years imprisonment can participate in the 2020 election," Little said.
The Waitangi Tribunal has said the ban breaches the Treaty because Māori are disproportionately imprisoned compared to other groups. The Supreme Court said it breached the Bill of Rights.
But National leader Simon Bridges told Magic Talk on Sunday prison is for the most serious offenders.
"I say, if you go to jail by definition you lose certain rights - you've lost your right to freedom, which is also a New Zealand Bill of Rights Act."
Bridges also believes a sentence under three years is still serious.
He told Magic Talk that many paedophiles, abusers and criminals who have committed serious crimes have been sentenced to under three years in prison.
He confirmed that a National-led government would take prisoners' rights to vote away because it was the right thing to do, in principle.
"What is very clear to me is ultimately Parliament is entitled as a question of values, not some sort of legal nicety."
He told host Roman Travers the Court of Appeal and Supreme Court are within their rights to make a declaration of inconsistency around the issue, but it's not a power they hold.
"It's the same point when it comes to the Waitangi Tribunal - they are entitled to their view, but Parliament set them up. It said their views were not mandatory and not binding."
Later this week National will be releasing a law and order discussion paper on what powers police need to do a good job, social investment, rehabilitation, reintegration and how to prevent crime.