Six entertainment-industry unions urged members to vote against Proposition 32, legislation that would prohibit guilds from using payroll deductions for political purposes.
The Directors Guild of America, SAG-AFTRA, IATSE, Professional Musicians Local 47, Teamsters Local 399 and IBEW Local 40 have long opposed the referendum, which they say would give redistribute power from the workers unions to "big corporations and billionaires."
"The DGA joins our fellow guilds and unions in vigorously opposing Proposition 32 and urging our members to vote 'no' on this misleading and disingenuous effort to inhibit union members from participating in political activity in California," the Directors Guild said in a statement.
Gabrielle Carteris, actor and the co-president of the Los Angeles SAG-AFTRA local, called the bill "a sham."
"It silences the voices of working Californians and infringes on their rights to fight for fair and evenhanded policies in Sacramento," she said in a statement.
She compared the proposition, which would limit unions' power to donate to candidates and super PACs, to the law passed in Wisconsin last year restraining guilds' collective bargaining rights.
"The backers of this proposition are some of the same anti-union backers of Wisconsin and the rest of our country," she said. "They have created a deceptive proposition that would allow them to funnel millions of dollars to candidates and parties in a continued assault on working families."