Arizona’s secretary of state determined on Thursday that advocates of a proposal to bar the use of affirmative-action preferences by public colleges and other state agencies had not submitted enough signatures to put the measure before voters in November.

The Arizona Civil Rights Initiative, the campaign organization behind the measure, needed 230,047 petition signatures from registered voters to get the proposed amendment to the state Constitution on the ballot. It turned in about 335,000, but Secretary of State Jan Brewer told the The Arizona Star that elections officials had declared all but 194,961 signatures to be invalid.

Advocates of the measure have not given up. Ward Connerly, who mounted the Arizona campaign as head of the American Civil Rights Institute and its related campaign organization, told the Star that he intended to direct campaign workers to gather evidence over the next several days to get some of the signatures restored.

If Ms. Brewer’s decision stands, it will be the third setback for Mr. Connerly in what was initially an effort to get five states to pass such bans this fall. His campaign organizations in both Missouri and Oklahoma failed this spring to gather enough signatures to get similar measures on the ballot in those states. His efforts in Colorado and Nebraska remain alive, but continue to face legal challenges. —Peter Schmidt