Casino mogul Sheldon Adelson has donated $10 million to the Koch brothers' efforts to elect Republicans and oust President Obama and other Democrats -- forging perhaps the most powerful, well-financed political fundraising machine of 2012.

Adelson donated the money last weekend during a Koch brothers' fundraising summit in suburban San Diego. The private deal was confirmed Friday, according to the Associated Press and other news agencies.

Adelson has already contributed $10 million to Restore Our Future, which is the super political action committee that backs GOP presidential candidate Mitt Romney, and $5 million each to two organizations promoting House Republicans.

During the GOP presidential primary, Adelson, chief executive officer of the Las Vegas Sands, and family members gave $21 million to a super PAC promoting former House Speaker Newt Gingrich.

Charles and David Koch are billionaire oil executives and libertarians who founded the small-government, anti-tax group Americans for Prosperity.