Michigan's Republican-led House and Senate are suing to preserve a law that makes it harder to qualify proposals for the statewide ballot.
Two lawsuits filed Wednesday in the Court of Claims and state appeals court seek to force Democratic Secretary of State Jocelyn Benson to follow the law enacted in December. Democratic Attorney General Dana Nessel has said key parts are unconstitutional.
The law says no more than 15% of petition signatures can be counted from a single congressional district.
Republicans say the legislation was a valid exercise of their right to enact voting laws and "ensure the integrity of the democratic process."
While Nessel's opinion is binding on state officials, courts will have the final say.
Voting-rights advocates and others recently sued to block the new requirements.