The Senate Leadership Fund, which is allied with Senate Majority Leader Mitch McConnell, plowed $25 million into Senate battleground states. | Getty Secret money fuels last-ditch GOP Senate blitz The super PAC got $11 million from a partner group that doesn't disclose its donors.

Much of the money supporting a Republican super PAC's last-minute investment in six key Senate races came from a linked organization that doesn't disclose its donors.

The super PAC, known as the Senate Leadership Fund, raised $18 million in the first 19 days of October, $11 million of which came from an allied nonprofit called One Nation, according to a report filed on Thursday with the Federal Election Commission. The organization is organized under a section of the tax code that allows it to engage in politics without having to disclose its donors.


The loophole has become an increasingly popular way for operatives in both parties to shield big-money donors from public scrutiny, despite the Supreme Court's reliance on transparency to justify opening the door to unlimited money in politics in the 2010 Citizens United decision.

A further $600,000 of the Senate Leadership Fund's haul came from American Crossroads, the secret money group started by Republican strategist Karl Rove.

The biggest named direct donor to the Senate Leadership Fund in the period was William Oberndorf, a San Francisco investor who gave $750,000. Investor John Childs; Michael Vlock, the Connecticut-based president of a windows manufacturer; former wrestling tycoon Linda McMahon; and Arkansas investment bank Stephens Inc., each gave $500,000. Blackstone chairman Stephen Schwarzman contributed $370,000.

The super PAC, allied with Senate Majority Leader Mitch McConnell (R-Ky.), plowed $25 million into Senate battlegrounds Indiana, Missouri, Nevada, New Hampshire, North Carolina and Pennsylvania, the group's president, Steven Law, told POLITICO earlier this week.

The group had $2.4 million left over as of Oct. 19, according to the FEC report.