Adelson, one of the world's richest men, is donating $10 million to the campaign activities of billionaire brothers Charles and David Koch. A person familiar with Adelson's pledge confirmed the donation Friday but requested anonymity to discuss the private arrangement.
During the GOP presidential primary, Adelson and members of his family gave $21 million to a super PAC promoting former House Speaker Newt Gingrich.
The Supreme Court's Citizens United decision in 2010 and other federal rulings ended restrictions on political contributions from corporations, labor unions, and millionaires and billionaires.
The Obama campaign has said he could become the first incumbent president to be outspent by his opponent and his opponent's supporters. -- AP