(Reuters) - The campaigns of presidential candidates are limited to receiving donations of up to $2,500 per person, once for the state-by-state party nominating season and again for the general election. But independent "Super PACs" have no limits on what they can raise from individuals, corporations or labor unions.
Here is a look at wealthy individuals who have contributed at least $500,000 to the major political action committees (PACs) as disclosed to the Federal Election Commission (FEC).
Total raised as of February 29: $43.2 million
(Supports former Republican Massachusetts Governor Mitt Romney)
Twenty-five donors gave more than $500,000 to the Super PAC. Below are those who donated at least $750,000.
* Bob Perry - Houston builder who was a major donor to Swift Boat Veterans for Truth in 2004 and is a longtime supporter of Texas Governor Rick Perry. Donation: $4 million
* F8 LLC and Eli Publishing - Provo, Utah-based firms that share an address. Both have been linked to former executives of Nu Skin. Total donations: $2 million
* John Paulson - a prominent New York hedge fund manager at Paulson and Co. Donation: $1 million
* Edward Conard - a New York investor and former executive at Bain Capital, a private equity firm co-founded by Romney. Donation: $1 million
* Julian Robertson - hedge fund industry legend at Tiger Management. Donation: $1 million
* Paul and Sandra Edgerly - Paul Edgerly, of Brookline, Massachusetts, is an executive at Bain. The Edgerlys each have given $500,000. Total donation: $1 million
* Robert Mercer - New York hedge fund manager at Renaissance Technologies. Donation: $1 million
* Paul Singer - hedge-fund manager who helped fund efforts to legalize gay marriage in New York. Donation: $1 million
* Rooney Holdings Inc - A private investment firm formed in 1980s to acquire the Manhattan Construction Co. and since expanding into many areas. Donation: $1 million
* J.W. Marriott Jr. - chairman and CEO of Marriott International, brother of Richard Marriott. Donation: $750,000
* Richard Marriott - chairman of Host Marriott International. Donation: $750,000
* Oxbow Carbon - a Florida-based firm run by Bill Koch that sells coke, a key ingredient in aluminum manufacturing. Donation: $750,000
* Chris Shumway - a prominent Connecticut hedge fund manager who got his start working with Robertson's Tiger Management. Donation: $750,000
Total raised as of February 29: $3.7 million
(Supports Texas Republican congressman Ron Paul)
* Peter Thiel - billionaire co-founder of online U.S. payment service PayPal; first outside investor in Facebook. Donation: $2.6 million
This list will be updated as more Super PACs file reports with the FEC before the midnight Tuesday deadline.