We just witnessed the most expensive election in history, with more "dark money" from secret sources than ever.

Big. Secret. Bucks.

Secretive non-profit groups obtained hundreds of millions of dollars and tried to influence the outcome of numerous races, without any disclosure of who was bankrolling these operations -- whether U.S. or global corporations or their CEOs.

Those using such shadowy groups include some of the richest people in the world, like David and Charles Koch who run one of the biggest corporations on the planet.

Some front groups spent hundreds of thousands of dollars on ads, calls, or mail, but operate out of a UPS drop box. Others operate as "shell companies" that cloak funding by other groups.

We must expose the Big Secret Bucks game to stop it.

One of the first steps we can take is to demand that the U.S. Senate investigate these secretive operations.

Join the Center for Media and Democracy in asking Senators to subpoena the Koch brothers and others involved in the big secret money game.