If the American presidential system were boiled down into a Las Vegas casino game, “Super PAC” betting would be placed exclusively in the high-stakes room.

The Super PAC system, a product of recent Supreme Court rulings, allows unlimited donations for political causes. And recent federal disclosure forms reveal the people behind them are the whales of the campaign trail — putting up donations frequently in excess of a quarter-million dollars.

For the first time, voters are getting a glimpse at who’s funding the previously opaque organizations boosting the presidential candidates’ campaigns with outside spending.