The campaign supporting the campaign finance-reform initiative raised about one-tenth over the same period.
Records filed with the California Secretary of State's Office show that the Teamsters, SEIU Local 1000 and the California Labor Federation has each donated $500,000 to fight the measure since Sept. 17.
Two politicians up for re-election on the Nov.6 ballot also kicked in to the No on 32 campaign. San Francisco Democratic Sen. Mark Leno gave $10,000. Assemblywoman Bonnie Lowenthal, D-Long Beach, gave $5,000.
Controller John Chiang gave $10,000. Chiang is termed out of office in 2014, but has a campaign committee to run for state treasurer that same year.
The donations pushed the No on 32 campaign's collections to $40.1 million through Friday.
Meanwhile, the Yes on Proposition 32 campaign took in about $165,000 during that same period. George Hume, chairman of San Francisco-based food processing company Basic American Foods, gave $100,000, according to state records. The Lincoln Club of San Diego County gave $50,000. The group's website says it supports "business-friendly candidates and ballot measures that reflect the Club's commitment to responsible public policy, the expansion of economic opportunity, and an enhanced quality of life throughout San Diego County."
The campaign finance reform measure on the Nov. 6 ballot would ban union and corporate contributions directly to candidates or their committees. Entities under government contract or negotiating for one would come under the same ban.
The measure doesn't curtail spending on so-called "independent expenditure" campaigns on ballot measures, however. The U.S. Supreme Court has ruled that limiting those kinds of contributions -- which aren't subject to the same disclosure rules as candidate contributions -- would violate Constitutional free-speech protections.
While corporations and unions could still spend freely on IEs, the measure would affect organized labors' ability to raise money for them, since Proposition 32 also bans payroll-deducted funds for political purposes. Unions raise their political money through that method. Corporations raise theirs via corporate resources and individual donations. Those avenues of fundraising remain open under Proposition 32.