CHULA VISTA, Calif. -- A proposition in Chula Vista is generating more controversy after a television commercial sparked outrage among its supporters.

Proposition G would prohibit Chula Vista from requiring union-only labor contracts on construction projects. Supporters called it “fair and open competition,” while opponents called it discrimination.

“And the people who put this on the ballot want to ban them from working in Chula Vista just because they’ve chose to join a union,” said Labor Council CEO Lorena Gonzalez. “That’s unfair.”

The union-backed No on G group produced a Spanish language commercial comparing Prop G to Arizona’s controversial immigration law. When translated, the ad said, “Proposition G in Chula Vista discriminates against our community.”

Yes on G supporter Francis Barraza said the ad an unfair comparison and said the issues were completely different.

Barraza also said the union have gone too far and accused them of trying to scare Mexican-Americans into voting against the proposition.

“I was horrified,” he said. “I was literally floored by the crazy imagery that I saw on the screen.”

The imagery included police surrounding protesters.

“I think it’s at the very least irresponsible and in my opinion, it’s shameful,” said Barraza.

Professor Miro Copic, who teaches marketing at San Diego State University, said the ad was misleading but is very effective.

“It’s a lot of scare tactics for an issue that shouldn’t have scare tactics,” said Copic. “This ad was specifically designed to create an emotional response with that target demographic.”

Gonzalez said the ad has been airing for a month without any complaints until now. In the meantime, she said Prop G would also limit the amount of state and federal funds Chula Vista could use to build its massive bayfront development.

“And unfortunately if Prop G passes, that puts that into jeopardy,” said Gonzalez.

Yes on G supporters argued the proposition is far from discriminatory but opens competition for jobs to everyone, including union and non-union workers.