AUSTIN, Texas — Efforts to put Austin's zoning laws before voters may be blocked by state law.

The process, known as CodeNEXT, has been underway for almost a half decade as the city tries to update its land development code to match the goals of Imagine Austin, the comprehensive plan adopted in 2012.

Members of IndyAustin, a Specific Political Action Committee or SPAC, have spent the past six months gathering the required signatures to force a public vote. Monday, the group said it has at least 20,000 signatures and plans to submit their petitions by the end of the month.

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In a memo to the Mayor and City Council, Austin City Attorney Anne Morgan shared advice from a neutral third party that says state law prohibits city leaders from calling elections on zoning.

"The city is not required or authorized to call an election on the initiative petition," attorney Robert Heath wrote in his opinion. "The citizen initiative is directed at a comprehensive revision of the zoning laws, and Texas courts have held that zoning is a subject that is outside the scope of the initiative and referendum process."

Additionally, Heath said the petition's call to override "all city charter provisions, ordinances and laws" exceeds the legal scope of a referendum petition.

'While an ordinance can repeal or supersede another ordinance, it cannot override a charter provision or a state law," Heath said.

IndyAustin is led by Linda Curtis, who lives in Bastrop County. The campaign received $45,000 from 10 donors, according to its most recent campaign finance report. That included $5,000 from billboard company Reagan Advertising and $17,000 from Texas Solutions Group, a government affairs firm.

Jim Skaggs, who lives just outside the City of Austin and has funded several previous campaigns against Austin initiatives--including the 2014 Urban Rail ballot measure and 2016 Mobility Bonds--gave $1,500 to IndyAustin, according to the most recent filing.