Legislation to remove the right to vote from anyone serving prison time passed its first debate in Parliament on Wednesday night.
At present, only prisoners sentenced to more than three years in jail are not allowed to cast a ballot.
But the member's bill, in the name of the National MP Paul Quinn, would extend that to everyone serving time.
Mr Quinn says people committing serious crimes still receive sentences of less than three years and the law should cover all prisoners.
The bill passed its first reading with support from ACT and United Future, and now goes to select committee for further consideration.
