Billionaire Sheldon Adelson may have blown $50 million more than previously thought on conservative candidates during the 2012 election.

Republican sources close to Adelson reportedly told The Huffington Post that the casino mogul may have lost $150 million trying to get candidates like former GOP nominee Mitt Romney elected, even though he had only promised to spend $100 million.

Up to $40 million of Adelson's money reportedly went to Karl Rove's Crossroads GPS, which only had a 14 percent success rate on the $70 million it spent. Adelson also doled out $15 million or more to groups with ties to billionaires Charles and David Koch, $5 million to the Chamber of Commerce and $6.5 million to the Republican Jewish Coalition.

In addition to non-profit groups, various super PACs received about $54 million from Adelson and his wife thanks to the U.S. Supreme Court's Citizens United decision, which allowed individuals and corporations to give unlimited amounts to outside groups.

Adelson, who is worth over $21 billion, told Politico earlier this year that he had been motivated to act because he felt vilified by the Obama administration after federal investigators began looking at his companies for possible money laundering in Las Vegas and bribery violations in connection to his China ventures.

"When I see what’s happening to me and this company, about accusations that are unfounded, that kind of behavior … has to stop," Adelson said before the election.

Adelson is scheduled to travel to Washington, D.C. this week where he will meet with at least one Republican leader to push for changes to the Foreign Corrupt Practices Act anti-bribery law, The Huffington Post's sources said.

[Photo: העין השביעית • / Flickr]