Hedge-fund managers made a big bet on Barack Obama and other Democrats in 2008. Now, with the 2012 contest gearing up, some prominent fund managers have turned their backs on the party and are actively supporting Republicans.

Daniel Loeb, founder of Third Point LLC, was one of the biggest Obama fund-raisers in 2008, rounding up $200,000 for him, according to campaign-finance records. In the decade prior, Mr. Loeb and his wife donated $250,000 to Democrats and less than $10,000 to Republicans.

But since Mr. Obama's inauguration, Mr. Loeb has given $468,000 to Republican candidates and the GOP, and just $8,000 to Democrats. Hedge-fund kings have feelings, too, and the president appears to have hurt them.

"I am sure, if we are really nice and stay quiet, everything will be alright and the president will become more centrist and that all his tough talk is just words," Mr. Loeb wrote in an email about four months ago expressing frustration with the president's posture toward Wall Street. "I mean, he really loves us and when he beats us, he doesn't mean it." The email, sent to eight friends, was widely circulated on Wall Street.

Mr. Loeb is part of a shift in political allegiance within the world of hedge funds that also includes such big names as Steven Cohen's SAC Capital Advisors and Kenneth Griffin's Citadel Investment Group. Managers and employees of hedge funds directed a majority of their contributions to the GOP in the 2009-2010 election season, a pattern not seen since 1996, when the industry was much smaller.