PHOENIX (AP) — A Superior Court judge in Arizona’s Maricopa County on Grant PrestonFriday denied a request from Republican state lawmakers to block a voter-approved law on transparency in campaign financing.

Judge Timothy Ryan refused to issue a preliminary injunction to stop the anti-dark money law. But he also said he would not dismiss the GOP challenge of Proposition 211, which was approved by Arizona voters more than a year ago.

Arizona Senate President Warren Petersen and House Speaker Ben Toma, both Republicans, had filed the challenge in August against Arizona’s Secretary of State Adrian Fontes.

They say the campaign finance law is unconstitutional because it violates the separation of powers. Because a commission is given the power to write the rules for the law, the Legislature is robbed of its lawmaking responsibility, they argue.

Voice messages were left at the legislative offices for Petersen and Toma seeking a response to the ruling. They were not immediately returned on Friday afternoon.

The law requires that major donors to electoral campaigns in Arizona be disclosed. Previously, they could be hidden by nonprofit groups that don’t have to name their contributors.

Voters passed the proposition on Nov. 8, 2022, with 72% of the vote, or about 1.7 million votes.

Ryan said in his ruling that there was no explanation for why the lawmakers took nine months to file their legal challenge. He also said that no mention was made of any pending legislation that could be affected by the voter-approved campaign finance law.

The office for Arizona’s Secretary of State did not immediately return an email seeking a reaction to the judge’s decision.