DES MOINES, Iowa (AP) – Opponents are suing to stop a new state rule that allows people to be removed from voter registration rolls if their citizenship is questioned.

The American Civil Liberties Union of Iowa and the Iowa League of United Latin American Citizens filed a lawsuit in Polk County District Court on Friday asking a judge to declare the rule illegal.

The rule is backed by Secretary of State Matt Schultz, a Republican. He says the change is needed to reduce voter fraud, which he’s made his key issue since taking office in 2011.

The civil rights groups stopped enactment of a similar emergency rule just before the November general election. But Schultz continued to pursue a permanent rule, which became effective on Wednesday.