INDIANAPOLIS (AP) — The Indiana secretary of state is appealing a ruling that a law stipulating voting requirements for a candidate’s party affiliation is unconstitutional in a decision that lifted the hopes of a U.S. Senate hopeful who wants to run as a Republican.

The Indiana attorney general’s office filed the notice of appeal Friday with the Indiana Supreme Court on behalf of Secretary of State Diego Morales.

The filing came a day after a Marion County judge granted an injunction sought by John Rust, former chair of the egg supplier Rose Acre Farms who is running to replace Sen. Mike Braun. Rust filed a lawsuit in September against Morales, the Indiana Election Commission and Jackson County Republican Party Chair Amanda Lowery to challenge the law and ensure the possibility of his place on the ballot.

The law in question says a candidate’s past two primary elections must be cast with the party the candidate is affiliated with or a county party chair must approve the candidacy. In court documents, Rust argued that this statute “should be struck down as being unconstitutionally vague and overly broad.”

A phone message seeking comment from Rust was left Friday evening by The Associated Press.

Rust voted as a Republican in the 2016 primary but as a Democrat in 2012. He did not vote in the 2020 Republican primary due to the pandemic and the lack of competitive Republican races in Jackson County, the lawsuit said. Rust said his Democratic votes were for people he personally knew.

Lowery, the county’s Republican Party chair, said in a July meeting with Rust that she would not certify him, the lawsuit said. Rust has said Lowery later cited his primary voting record.

In a November hearing, Rust said the law keeps legitimate candidates who have recently moved to Indiana or have switched political identifications from running for office.

In his ruling, Marion County Superior Court Judge Patrick J. Dietrick said the law “unduly burdens Hoosiers’ long recognized right to freely associate with the political party of one’s choosing and to cast one’s vote effectively.”

Should Rust prevail, he still faces an uphill challenge for the GOP nomination. U.S. Rep. Jim Banks has received the endorsement of the Indiana Republican Party and former President Donald Trump. Rust must also fulfill a signature quota for the nomination.

Casting himself as a conservative gay man with an “outsider’s voice” to Washington D.C., Rust is the former chair of his family business Rose Acre Farms in southern Indiana. Rose Acre Farms identifies itself as the second-largest egg producer in the U.S.

The company was one of four major egg producers in the country accused of fixing the price of eggs in the 2000s. A jury in an Illinois federal court recently ruled the producers conspired to limit the domestic supply of eggs to increase prices between 2004-2008 and ordered the companies to pay $17.7 million in damages. Rose Acre Farms has denied any wrongdoing.

Sen. Mike Braun is vacating the seat in his bid for governor.