(CBS News) Super PACs, the political action committees permitted to accept and spend unlimited sums of money, are revealing an ever-widening roster of mega-donors. Through August, more than 60 donors gave at least $1 million to super PACs, which are required to disclose their donors' names and amounts.
At least 26 people or companies gave $1 million or more to the main super PAC supporting Mitt Romney, Restore Our Future, which had raised a cumulative $97 million by the end of August and spent $90 million. Its donor list included 25 billionaires.
At least 16 people or labor unions gave at least $1 million or more to the main super PAC supporting President Obama, Priorities USA Action, which had raised $43 million through August and spent $35 million. At least three billionaires gave to the pro-Obama group.
Super PACs supporting various candidates and causes have already spent a combined $270 million during Campaign 2012, according to the Center For Responsive Politics and the Sunlight Foundation, two non-profit research organizations tracking the money flow.
The Super PAC with the most money in the bank entering September was American Crossroads, the Republican-backing group co-founded by Karl Rove and Ed Gillespie. It had $32 million cash on hand, or quadruple the funds of the next most cash-rich group, House Majority PAC, which supports Democrats running for the U.S. House of Representatives.
Each of the nation's three leading super PAC donors - Sheldon Adelson, Harold Simmons, and Bob Perry - are conservatives who have contributed double-digit millions to a number of groups. They are soon to be joined by Joe Ricketts, who has stated he would spend $10 million of his fortune on political advertising this campaign season. A spokeswoman confirmed today that Ricketts did give another $10 million this month to Ending Spending Fund, a super PAC he founded.
As eye-popping as some of these donation totals may be, they do not include additional contributions by many of these donors to candidates' campaigns, to political parties, or to non-profits not required to disclose their donors. The latter category includes three conservative groups -- Americans For Prosperity, which has already spent $30 million on election activities, and the U.S. Chamber of Commerce and Club For Growth Action, which have each spent $13 million.
Here are the top 20 super PAC donors based on a CBS News review of their reports to the Federal Election Commission:
1. Sheldon Adelson & Family. Total: $37.5 million
Adelson is CEO of the Las Vegas Sands Corp.
Billionaire Adelson and his wife, Miriam, gave pro-Romney Restore Our Future $10 million in June. During the primary campaign, the Adelsons and their children bet heavily on Newt Gingrich, giving pro-Gingrich Winning Our Future $21.5 million; $5 million was refunded in May. The Adelsons are gave $5 million to the Congressional Leadership Fund, which supports Republican candidates for the House of Representatives, $5 million to the YG Action Fund, which supports conservative "young guns" running for office, and $1 million to Freedom PAC, which supports Florida Congressman Connie Mack's run for the U.S. Senate.
2. Harold Simmons/Contran. Total: $18.7 million
Simmons is CEO of Dallas-based holding company Contran Corp. and publicly-traded Valhi.
Billionaire Simmons and his company, Contran, gave $13 million to pro-Republican American Crossroads, $1.1 million to pro-Gingrich Winning Our Future, $1.1 million to two groups supporting Texas Governor Rick Perry, and $800,000 to the pro-Romney Restore Our Future. His wife, Annette, gave $1.2 million to pro-Rick Santorum Red White and Blue Fund. Simmons also gave $1.5 million to a pair of groups which promoted the U.S. Senate candidacy of Texas Republican David Dewhurst, who lost the primary to Ted Cruz - Conservative Renewal and the Texas Conservatives Fund - and $25,000 to Strong Utah, which supports Republican Senator Orrin Hatch.
3. Bob Perry. Total: $15.9 million
Perry is a Houston-based homebuilder and president of Perry Homes.
Perry gave $8 million to pro-Romney Restore Our Future and $6.5 million to American Crossroads. He also gave $1 million to the Congressional Leadership Fund, focused on electing Republicans to Congress, $300,000 to the Texas Conservatives Fund, which promoted the U.S. Senate candidacy of Texas Republican David Dewhurst, who lost the primary to Ted Cruz, and $100,000 to Make Us Great Again, a super PAC supporting Texas Governor Rick Perry.
4. Peter Thiel. Total: $4.7 million
Thiel is CEO of Clarium Capital Management, in Palo Alto, Calif.
Billionaire Thiel gave $2.6 million to pro-Ron Paul Endorse Liberty and $135,000 to pro-Paul Revolution PAC. He also gave $2 million to Club For Growth Action, which advocates for lower taxes.
5. Robert Rowling. Total: $4.13 million
Rowling is president of TRT Holdings, a Texas firm which owns Omni Hotels and Gold's Gyms.
Billionaire Rowling and his company gave $4 million to pro-Republican American Crossroads, $100,000 to pro-Romney Restore Our Future, and $35,000 to Texas Conservatives Fund, which promoted the U.S. Senate candidacy of Texas Republican David Dewhurst, who lost the primary to Ted Cruz.
6. James Simons. Total: $4 million
Simons is President of Euclidean Capital, a New York investment firm.
Simons gave $2 million to pro-Obama Priorities USA Action. He also gave $1.5 million to Majority PAC, which supports Democrats running for U.S. Senate, and $500,000 to House Majority PAC, which supports Democrats running for the U.S. House of Representatives.
7. Steve Mostyn & Amber Anderson. Total: $3.35 million
Mostyn and Anderson are married partners in the Mostyn Law Firm, in Houston.
Mostyn, the current president of the Texas Trial Lawyers Association, and his wife, who handles personal injury and wrongful death cases, gave a combined $2 million to pro-Obama Priorities USA Action, $1 million to the House Majority PAC, which supports Democrats running for the U.S. House of Representatives, $200,000 to Planned Parenthood Votes, and $125,000 to Texans For America's Future, which opposed Rick Perry's presidential run.
8. Robert Mercer. Total: $3.3 million
Mercer is co-CEO of Renaissance Technologies, a hedge fund in New York.
Mercer gave $1 million to pro-Romney Restore Our Future and $1 million to pro-Republican American Crossroads. He also gave $600,000 to Club For Growth Action, which advocates for lower taxes, $500,000 to Prosperity First, which opposes the re-election of Democratic New York Congressman Tim Bishop, Mercer's congressman, and $200,000 to National Horizon, which supports certain conservative candidates for Congress.
9. Fred Eychaner. Total: $3.25 million
Eychaner is President and CEO of Chicago-based Newsweb Corp., which owns newspapers and radio stations.
Eychaner gave $1.5 million to pro-Obama Priorities USA Action, $800,000 to pro-Senate Democrat Majority PAC, and $750,000 to pro-Democratic House Majority PAC. He also gave $200,000 to the America Votes Action Fund, which promotes progressive causes.
10. John Childs. Total: $3.125 million
Childs is CEO of the Florida investment firm J.W. Childs Associates.
Childs gave $1 million to pro-Romney Restore Our Future, $1 million to pro-Republican American Crossroads, and $1.125 million to Club For Growth Action, which advocates for lower taxes.
11. Harlan Crow. Total: $3.1 million
Crow is Chairman and CEO of Crow Family Holdings, a real estate firm based in Dallas.
Crow Holdings gave $1.5 million to pro-Republican American Crossroads. The company, Harlan, and his brother Trammel gave a combined $1.3 million to the pro-Romney Restore Our Future. The company gave $250,000 to FreedomWorks, which focuses on grassroots action for economic conservatives, $50,000 to Texas Conservatives Fund, which promoted the U.S. Senate candidacy of Texas Republican David Dewhurst, who lost the primary to Ted Cruz, and $35,000 to the Campaign For Primary Accountability, which opposes certain congressional incumbents.
12. William Koch. Total: $3 million
Koch is the founder and CEO of Oxbow Carbon, a Florida energy company.
Billionaire Koch and his companies gave $3 million to the pro-Romney Restore Our Future. He is less well-known than his brothers Charles and David, who are prolific backers of conservative causes.
13. John Ramsey. Total: 2.76 million
Ramsey, from Austin, Tex., is the heir to a real estate and banking fortune.
Ramsey, 21, a college student, gave $2.76 million to Liberty For All, a super PAC he founded that backs libertarian candidates for Congress.
14. Amy Goldman. Total: $2.75 million
Goldman is an heir to a New York real estate fortune, a philanthropist, and an author.
Goldman gave $1 million to pro-Obama Priorities USA Action and $250,000 to American Bridge 21st Century, which supports Democratic candidates with opposition research and tracking. She also gave $1 million to Planned Parenthood Votes and $500,000 to House Majority PAC, which supports Democrats running for the U.S. House of Representatives.
15. Jerry Perenchio. Total: $2.6 million
Perenchio, from Los Angeles, is the former owner of Univision Spanish language television and chairs the investment firm Chartwell Partners.
Billionaire Perenchio gave $2 million to pro-Republican American Crossroads, $500,000 to pro-Romney Restore Our Future, and $100,000 to pro-Jon Huntsman Jr. Our Destiny.
16. Foster Friess. Total: $2.4 million
Friess is a Wyoming-based investor and founder of the firm Friess Associates.
Friess gave $2.1 million to pro-Santorum Red White and Blue Fund. After Santorum quit the race, Friess gave $100,000 to pro-Romney Restore Our Future. He also gave $100,000 to FreedomWorks for America, which focuses on grassroots action for economic conservatives, $50,000 to Leaders for Families, a socially conservative group that was active in the Iowa caucuses, and $25,000 to Friends of the Majority, which opposed Arizona Rep. David Schweikert's victory over fellow Republican Rep. Ben Quayle in an August primary.
17. William Dore. Total: $2.25 million
Dore is President of Dore Energy Corporation, in Lake Charles, La.
Dore gave $2.25 million to pro-Santorum Red White and Blue Fund.
18. Jon Huntsman, Sr. Total: $2.222 million
Huntsman is CEO of Utah-based Huntsman Corporation and the father of former Republican presidential candidate Jon Huntsman.
Huntsman gave $2.2 million to Our Destiny, the super PAC that supported his son's candidacy.
19. Paul Singer. Total: $2.220 million
Singer is the founder & CEO of Elliot Management Corp., a hedge fund in New York.
Billionaire Singer gave $1 million to pro-Romney Restore Our Future and $100,000 to Club For Growth Action, which advocates for lower taxes. Singer also gave $1.12 million to launch American Unity PAC, which backs Republican candidates who support gay marriage.
20. Jeffrey Katzenberg. Total $2.15 million
Katzenberg is CEO of DreamWorks Animation in California.
Katzenberg gave $2 million to pro-Obama Priorities USA Action and $100,000 to Majority PAC, which supports Democrats running for U.S. Senate. He also gave $25,000 to the Committee To Elect An Effective Valley Congressman, which supports the San Fernando Valley region in California, Democratic Rep. Howard Berman.