Casino mogul Sheldon Adelson is giving $10 million to the 2012 election efforts of the Koch brothers, a Republican Party insider in Nevada confirms.

Las Vegas Sands Corporation's CEO Sheldon Adelson attends Sands China's 2010 Annual General Meeting in Hong Kong in this June 19, 2010 file photo. (TYRONE SIU/REUTERS)

Charles and David Koch, billionaire libertarians in the oil industry, are involved in an array of outside groups aimed at defeating President Obama and other Democrats this November. They plan to spend about $400 million on the election.

The donation was first reported by Politico, which adds that Adelson made his pledge at a Koch donor convention in San Diego this past weekend — another sign of how powerful a force the brothers have become in the GOP.

The Kochs are behind American for Prosperity, a non-profit group has already spent millions of dollars into ads attacking Obama and other Democrats. They’re also reportedly behind Themis, a voter information database meant to rival Democrats’ Catalist. Koch influence and funds also trickle down to various anti-Obama groups.

Adelson’s donations confirms that he intends to be one of the very top players in this election. He has already given $10 million to Restore Our Future, a super PAC run by ex-aides and associates of former Massachusetts governor Mitt Romney.

According to the Huffington Post, Adelson has also committeed at least $10 million to the Crossroads Grassroots Policy Strategies, a pro-Republican group advised by Karl Rove, and $5 million each to two groups backing GOP House candidates.

A major supporter of former House speaker Newt Gingrich in the Republican primary, Adelson was the largest single donor to Romney’s super PAC. His politics are defined mostly by his support for conservative politics in Israel and his opposition to unions in the U.S.

He’s the eighth-richest man in the world, and his increasingly investment in Republican outside groups will only increase fear among Democrats that they will be swamped by GOP spending this cycle.