Proposition 32 also places a similar ban on corporations for use in state and local political campaigns, but most don't deduct funds from paychecks for political activities anyway. For that reason, the measure is seen as an effort to limit the political influence of unions in California.
"The main issue behind Proposition 32 is it would have a profound impact on us," said Maria Elena Durazo, executive secretary-treasurer of the Los Angeles County Federation of Labor, AFL-CIO.
"It was put on the ballot by some wealthy individuals who want to fight the right of everyone else to be able to speak up for their rights. It is not about union members.
"It is about farm workers who don't have a voice and die in the fields. ... It is about protecting workers' standards," Durazo said.
Unions have raised an estimated $50 million to defeat the measure, while corporations and other supporters have raised at least $30 million.
The measure proposed by attorney Thomas A. Willis has received strong financial support from Charles Munger Jr. -- a Stanford physicist whose father is a billionaire -- and former Univision CEO Jerry Perenchio, among others, and has received $4 million from the national conservative super PAC American Future Fund.
Supporters of the measure argue it would help reduce the influence of unions in electing officials, primarily Democrats, as well as contractors from lobbying government officials.
However, the measure exempts independent expenditure committees and other large contributors.
"I think it levels the playing field," said Jon Coupal, president of the Howard Jarvis Taxpayers Association. "I think it is hugely important to sever the ties between politicians and unions and corporations."
Jake Suski, a spokesman for the Yes on 32 campaign, said its goal is to "cut the money ties between politics and corporations and unions.
"It ensures every single contribution is made voluntarily and can't be deducted from their paycheck for political purposes," Suski said.
He acknowledged most corporations in California do not have paycheck deductions because they are allowed to contribute directly to campaigns.
Independent polls show the No on 32 side is leading, but Suski said they hope to persuade voters it is a step to getting a more responsive government.
"Voter are frankly more and more frustrated with government serving the interests of only the most well-funded and narrow special interests," Suski said.
"When it comes to issues like pensions, the open primary law and taking redistricting out of the hands of politicians, it is all about empowering the electorate and developing a more accountable system."
Proposition 32YES means: Unions and corporations could not use money deducted from an employee's paycheck for political purposes. Unions, corporations and government contractors would be subject to additional campaign finance restrictions.
NO means: There would be no change to existing laws regulating the ability of unions and corporations to use money deducted from an employee's paycheck for political purposes. Unions, corporations and government contractors would continue to be subject to existing campaign finance laws.