Maine could join at least 17 states that automatically register voters.
The Senate sent the bill to Democratic Gov. Janet Mills Tuesday.
Maine would automatically register voters who do business with the Bureau of Motor Vehicles by 2022 under the bill, which has a one-time cost of $140,000 federal funds. Maine's Secretary of State could also allow certain groups like private colleges to help automatically register voters.
The National Conference of State Legislatures says 17 states have automatic voter registration.
The bill also allows 16-year-olds to conditionally vote and enroll in a political party down from 17.
An amendment requires individuals to be notified that they can opt-out, and for registrars of voters to determine eligibility.
The Maine Heritage Policy Center warns the change will lead to fraud.