WASHINGTON — At a private three-day retreat in California last weekend, conservative billionaires Charles and David Koch and about 250 to 300 other individuals pledged approximately $100 million to defeat President Obama in the 2012 elections.

A source who was in the room when the pledges were made told The Huffington Post that, specifically, Charles Koch pledged $40 million and David pledged $20 million.

The semi-annual, invitation-only meeting attracts wealthy donors, Republican politicians and conservative activists. Last year, hundreds of activists gathered outside the walled-off resort to protest the meeting. This year, however, the conference went off quietly.