Co-founders of online U.S. payment service PayPal, now owned by eBay Inc, donated to the Super PAC funding group supporting Republican presidential candidate Ron Paul, the group Endorse Liberty disclosed on Tuesday.

PayPal co-founders Peter Thiel and Luke Nosek and Scott Banister, an early adviser and board member, put their support behind the Endorse Liberty Super PAC, alongside Internet advertising veteran Stephen Oskoui and entrepreneur Jeffrey Harmon, who founded Endorse Liberty in November.

Texas congressman Ron Paul, a libertarian, has been an unconventional candidate for the 2012 Republican presidential nomination, advocating an isolationist brand of foreign policy and a $1 trillion cut in the U.S. government's budget.

Too often in this country we learn things the hard way ... With its unsustainable deficits, government spending is heading down the same path. Men and women who want freedom and growth should take action. A good place to start is voting for Ron Paul, Thiel said in a statement.

Thiel, a libertarian activist whose $1.5 billion in wealth ranked him 833 on the Forbes top billionaires list last year, became the first outside investor in social networking service Facebook in 2004.

Releasing the donor list before officially filing with the Federal Election Commission, Endorse Liberty founders said they raised $3.9 million to support Paul, who failed to win any of the first three state-by-state Republican nominating contests.

Republicans are voting in the Florida primary on Tuesday. Paul trails frontrunners Mitt Romney and Newt Gingrich in most polls in the state, but he is seen as having a better chance in Nevada, which votes next.

Endorse Liberty founders have so far reported spending about $3.3 million promoting Paul by setting up two YouTube channels, constantly buying ads from Google and Facebook and StumbleUpon and building up a presence on the Web.

PayPal began as an independent company, founded in the late 1990s by technology entrepreneurs, including venture capital investors Thiel and Nosek. The business battled with eBay for supremacy in the emerging online payments market. But soon after it went public in 2002, eBay acquired PayPal for $1.5 billion.

Endorse Liberty also received donations from James O'Neill and Jonathan Cain, who now run the Thiel Foundation that seeks to defend and promote freedom in all its dimensions: political, personal, and economic, according to its website.

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