California voters are poised to become the largest electorate to decide whether to support a constitutional amendment that would overturn the U.S. Supreme Court’s Citizens United ruling.

California Assemblymember Bob Wieckowski (D-Fremont) introduced a bill, AB 644, Wednesday to put a measure on the state’s 2014 ballot urging Congress to pass a constitutional amendment to overturn the 2010 Citizens United ruling, which lifted restrictions on political spending by corporations and labor unions. Independent spending in federal elections has exploded since the ruling.

“It’s one thing for a legislator to say he wants this,” Wieckowski said. “It’s another thing for Congress to have direct instruction from the voters. There comes a tipping point where people are upset with billionaires having a disproportionate impact on our electoral system.”

The measure is backed by campaign finance watchdog Common Cause. The group’s growing effort includes ballot questions that allow voters in cities and states to weigh in on Citizens United.

“Giving the voters of the most populous state, the world’s ninth-largest economy, the chance to declare that Citizens United should be reversed would be historic and the momentum this reform movement needs to sweep the nation,” said Phillip Ung, policy advocate for Common Cause. “As goes California, so goes the nation.”

Hearing directly from voters, Wieckowski said, will force more local politicians to get behind campaign finance reform. “For example, if a Republican legislator in Orange County saw 60 percent of his district vote to overturn Citizens United, he’ll realize, ‘Oh my God, that’s empirical evidence,'” Wieckowski said.

Last November, voters in Montana, Colorado and 175 cities, including Chicago, San Francisco, and more than half the cities in Massachusetts, passed measures instructing Congress to support a constitutional amendment to overturn Citizens United.

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