LITTLE ROCK, Ark. (AP) — Supporters of an effort to impose stricter term limits on Arkansas legislators on Thursday filed a lawsuit challenging new restrictions placed on initiative campaigns.

Arkansas Term Limits, U.S. Term Limits and Liberty Initiative Fund asked a federal to strike down the new restrictions, approved this year by the state Legislature. The restrictions include a requirement that signature gatherers be residents of the state, and another prohibiting campaigns from paying per signature.

The lawsuit argues the restrictions are unconstitutional and will hamper citizens’ abilities to put measures on the ballot.

“This lawsuit is necessary to prevent legislation from impairing clearly established rights under the federal constitution passed by a runaway and vindictive state legislature intent on preventing the citizens of Arkansas from exercising their right to bypass the power of unresponsive legislators,” the groups’ lawsuit said.

Secretary of State John Thurston, who is named as the defendant in the lawsuit, declined to comment on the filing, a spokeswoman said.

The groups are trying to put a proposed constitutional amendment on next year’s ballot that would impose a 10-year limit on serving in the Arkansas Legislature. Under the proposal, lawmakers could not be elected to more than three two-year terms in the House of Representatives or more than two four-year terms as a senator, with a cumulative limit of 10 years.

Voters last year approved an amendment Arkansas lawmakers placed on the ballot that set a 12-year term limit for the Legislature but allows legislators to return after a four-year break.