SACRAMENTO -- California emerged Thursday at the center of the national debate over the influence of shadowy super PACs, as the state's political watchdog filed suit against a Phoenix group that made an anonymous $11 million contribution to defeat Gov. Jerry Brown's tax-hike initiative and boost an anti-union ballot measure.

The surprise contribution -- believed to be the largest anonymous political donation in state history -- last week stunned the governor and the labor and education groups working to pass Proposition 30, a tax-hike initiative that Gov. Jerry Brown claims is vital to adequately funding K-12 education and state colleges and universities. Under furious assault from negative ads, the measure is sliding in the polls.

Ann Ravel, the chairwoman of the Fair Political Practices Commission, is suing to force disclosure of information about Phoenix-based Americans For Responsible Leadership. That group made the contribution last week to the Small Business Action Committee, a political action committee running ads against Proposition 30 and for Proposition 32, which would bar unions from collecting union dues for political purposes.

"It's incredibly important to the public to know who is spending money on campaigns in California to influence the electorate," Ravel told this newspaper. "People make decisions based on information about the different sides and the identities of different groups. And we're getting so close to the election that we're asking for expedited action."

Attorney General Kamala Harris joined the lawsuit, filed in Sacramento County Superior Court.

The $11 million is just a fraction of the hundreds of millions of dollars unleashed by the 2010 U.S. Supreme Court's Citizens United decision, which allowed unlimited contributions from corporations and wealthy individuals into campaigns. But the donation peeled back layers on the secretive web of political organizations that tie some of the nation's largest super PACs to the previously unknown group in Arizona.

The Supreme Court ruling has created a perfect storm, said Tracy Westen, founder of the Los Angeles-based Center for Governmental Studies. "There's more money and more secrecy," Westen said Thursday. "And you have to assume that contributors are withholding their identity because they think their identity might undermine their message."

The law firm for Americans for Responsible Leadership is run by Jill Holtzman Vogel, a Republican legislator in Virginia and chief counsel for the Republican National Committee. Her firm shares office space with GOP uber-strategist Karl Rove, whose American Crossroads super PAC has poured hundreds of millions of dollars into campaigns this year. It also has done work with groups affiliated with David and Charles Koch, the conservative oil magnate brothers who are pouring huge sums into campaigns across the country.

As a 501(c)4 nonprofit organization, Americans for Responsible Leadership is not required by federal law to disclose its donors. But California law requires that outside nonprofits must reveal their donors if they knew or should have known that their money would go toward political purposes in California.

A Superior Court judge scheduled a hearing for Tuesday to determine whether the FPPC has the right to conduct an audit of the Arizona group and the Small Business Action Committee.

A new FPPC rule assumes that donors to politically active groups are presumed to know they are making political donations, Ravel said.

Attorneys for the Arizona group accused the FPPC of using the courts to further a political fight being led by Brown, who has made it a rallying cry in his Proposition 30 campaign to "unmask" the donors.

"This motion is a result of intense political pressure to have the FPPC 'do something' to keep this campaign issue alive," Bradley Benbrook, a Sacramento attorney retained by the group's Virginia law firm, wrote in a brief opposing the lawsuit. "Bowing to political pressure, the FPPC has forged ahead with the litigation at warp speed."

Attorneys for the group argued in papers filed Thursday with the court that they didn't break state law because donors' contributions were not earmarked for political purposes.

Attorney Jason Torchinsky said in a letter to the FPPC that it cannot conduct an audit until after Jan. 13, the last day of filing final campaign finance reports following the election.

Ravel's decision to go to court was applauded by Derek Cressman, regional director for the good-government group Common Cause, which filed a complaint with the FPPC last week seeking disclosure of the donors.

"Today's lawsuit will compel important records from Americans for Responsible Leadership and will allow the public to see the truth behind the deception," Cressman said.

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