SAN DIEGO (CNS) - Supporters of a proposal to reform the governing structure of the San Diego Unified School District expressed disappointment Tuesday that they failed to gather enough signatures to qualify the measure for the ballot.

Members of "San Diegans 4 Great Schools" needed to collect more than 93,000 valid signatures and came up 3,000 short, despite turning in more than 129,000 names, according to the San Diego City Clerk's Office.

The most controversial part of the plan was to add four appointed members to the five-person Board of Education.

The proposal also called for 12-year term limits and other reforms that, according to backers, would have reduced the influence of special interests, increased support to teachers and given parents the tools to keep the district accountable.

"We're very disappointed to learn that our measure failed to qualify for the ballot," said Scott Himelstein, a supporter of the measure. "However, we're proud that we started an important conversation on school reform and we hope to see it continue."

The clerk's office reported that the measured failed, in part, because 22,520 people who signed the petitions were not registered to vote and 14,746 duplicate signatures were found in the tabulation conducted by the county Registrar of Voters.