SACRAMENTO -- The shadowy Arizona group that gave $11 million to a small-business PAC has nothing on Charles Munger Jr.

Munger, a Republican activist from Palo Alto, has been the true deep pockets of the Small Business Action Committee, which is running campaigns in favor of Proposition 32 -- the measure that seeks to curb unions' ability to collect political dues -- and against Proposition 30, Gov. Jerry Brown's tax-hike measure.

After donating a cool $13 million to the business group Friday, Munger has now contributed $36.5 million of the $49 million the PAC has raised, according to Berkeley-based Maplight, a nonpartisan group that tracks campaign spending.

A third of all money spent on ballot measures has gone into Proposition 32, with labor and business interests combining for $117 million, according to the latest campaign finance documents that had to be filed by midnight Thursday. Labor groups have barely out-raised their rivals, $59.1 million to $57.7 million.

The Fair Political Practices Commission, the state's political watchdog, filed suit Thursday against the Phoenix-based Americans for Responsible Leadership for refusing to disclose who donated the $11 million to the small-business PAC.

Munger still hasn't caught up to his half-sister, Molly Munger, who, along with her husband, Steve English, have thrown $47.4 million into her campaign for Proposition 38, which would raise taxes on all but the poor to fund schools.

Molly Munger may soon surpass the single largest individual donor in California ballot measure history: Hollywood producer Stephen Bing, who spent $49.6 million in the failed 2006 effort to pass Proposition 87, which would have raised taxes on oil companies.

"I don't think it comes as a surprise to voters that the wealthy have taken a lot of interest in the power of the initiative and its ability to push their pet projects and proposals," said Philip Ung, lobbyist for California Common Cause, which is pushing campaign finance reform. "Grass-roots can rarely, if ever, get an initiative qualified or passed."

Together, the Mungers, whose father Charles Munger Sr. is multibillionaire Warren Buffett's partner at Berkshire Hathaway, have donated $83.9 million this year. That's nearly a third of the approximately $345 million spent so far on November ballot measures.

Another wealthy individual, San Francisco hedge fund manager Tom Steyer, has spent $29 million on Proposition 39, which would require out-of-state companies to use the same tax formulas as California firms. Mercury Insurance chairman George Joseph has poured $16.4 million into Proposition 33, the auto-insurance measure that would allow drivers with continuous coverage to switch policies without losing their "loyalty discounts," but would also allow insurance companies to charge steep surcharges for those who haven't kept up their coverage.

Of the ballot measures with heavy support from wealthy individuals, only Steyer's appears to be heading toward victory. Both Propositions 32 and 38 are below 50 percent support in polls.

"The wealthy can spend as much money as they want on initiatives, but California voters always have an independent mind," Ung said.

Among organizations who contributed to ballot measures, the California Teachers Association ranked at the top with $31.4 million, followed by the Service Employees International Union at $20.7 million.

Contact Steven Harmon at 916-441-2101. Follow him at Twitter.com/ssharmon. Read the Political Blotter at IBAbuzz.com/politics.