TAMPA, Fla. (Reuters) - Seven former felons sued Florida Governor Rick Scott and other state officers on Monday seeking to have their voting rights restored, claiming their disenfranchisement in the state is unconstitutionally arbitrary.

Florida is one of four states that strip all former felons of their voting rights. The class action lawsuit filed in the U.S. Northern District of Florida by the non-partisan Fair Elections Legal Network takes aim at the process by which they can seek to regain their voting rights.

Measures adopted in 2011 by Scott and other Republican state leaders require ex-felons to wait for five to seven years after completing their sentences before they can apply to regain their vote.

Fewer than 2,500 petitions for voting rights restoration have been approved since Scott took office in 2011, while the backlog of applications stands around 10,500, the lawsuit said.

Florida’s approach has disenfranchised an estimated 1.6 million people, more than any other state, research shows.

The state has maintained some of the nation’s toughest voting rights restrictions, while many other states have taken steps to help convicted criminals regain access to the ballot after the completion of their sentences.

Racial minorities are disproportionately impacted by the felon voting restrictions in Florida, which is the largest battleground state in U.S. presidential elections.

“Florida’s voting rights situation has become just an unmitigated crisis,” said Jon Sherman, senior counsel with the Washington-based Fair Elections Legal Network, which is working with the firm Cohen Milstein Sellers and Toll.

State rules give Scott the deciding vote in serious cases on felon voting rights restoration that are heard in person before a clemency board composed of the governor and state cabinet officers.

He has denied petitions over traffic tickets incurred after sentences were completed, the lawsuit said. It noted that he asks some, but not all, petitioners to account for histories of alcohol and substance abuse.

Scott’s office said it was reviewing the lawsuit.

“When it comes to the restoration of voting rights for felons, Governor Scott believes that they have to demonstrate that they can live a life free of crime, show a willingness to request to have their rights restored, and show restitution to the victims of their crimes,” spokeswoman Jeri Bustamante said in a statement.

Groups including the American Civil Liberties Union of Florida are working on a ballot initiative to restore many felons’ voting rights, barred for more than a century in the state constitution.